Download Lab Packet - Auburn University

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VERTEBRATE DEVELOPMENT, BIOL 4410
LABORATORY HANDOUTS
FALL 2016
(revised 2/2/16)
INSTRUCTOR - DR. STEPHEN C. KEMPF
DEPARTMENT OF BIOLOGICAL SCIENCES
AUBURN UNIVERSITY
1
TABLE OF CONTENTS
LECTURE, LAB READING, SLIDE #s, AND EXAM SCHEDULE ------------------------
3
COURSE POLICIES --------------------------------------------------------------------------------
10
LABORATORY REQUIREMENTS/INFORMATION ---------------------------------------
11
LAB NOTEBOOK REQUIREMENTS -----------------------------------------------------------
12
LAB NOTEBOOK – FREQUENTLY ASKED QUESTIONS -------------------------------
14
POSSIBLY USEFUL STUDY HINTS -----------------------------------------------------------
16
LAB EXAM AND QUIZ SAMPLE QUESTIONS ---------------------------------------------
17
HANDOUT 1A, LABORATORY ORIENTATION -------------------------------------------
20
HANDOUT 1B, USE OF THE COMPOUND MICROSCOPE -------------------------------
23
HANDOUT 2A, ROUTINE METHODS ---------------------------------------------------------
29
HANDOUT 2B, MITOSIS, MEIOSIS, AND GAMETOGENESIS --------------------------
35
HANDOUT 2C, BASIC MICROSCOPY METHODS -----------------------------------------
37
LABORATORY ID LISTS – OVERVIEW -----------------------------------------------------
42
HANDOUT 3A, REPRODUCTIVE ORGANS: SPERMATOGENESIS -------------------
43
HANDOUT 3B, REPRODUCTIVE ORGANS: OOGENESIS -------------------------------
44
HANDOUT 4A, STARFISH DEVELOPMENT -----------------------------------------------
45
HANDOUT 4B, EARLY FROG DEVELOPMENT --------------------------------------------
46
HANDOUT 5, 4 - 7 MM FROG TADPOLE -----------------------------------------------------
48
HANDOUT 6, 10 MM FROG TADPOLE --------------------------------------------------------
51
HANDOUT 7A, CRANIAL NERVES AND GANGLIA --------------------------------------
54
HANDOUT 7B, 18 AND 24 HOUR CHICK -----------------------------------------------------
58
HANDOUT 8, 33 HOUR CHICK ------------------------------------------------------------------
60
HANDOUT 9, 48 HOUR CHICK ------------------------------------------------------------------
62
HANDOUT 10, 72 HOUR CHICK -----------------------------------------------------------------
65
HANDOUT 11, 96 HOUR CHICK -----------------------------------------------------------------
72
HANDOUT 12, 6 MM PIG --------------------------------------------------------------------------
78
HANDOUT 13, 10 MM PIG -------------------------------------------------------------------------
83
HANDOUT 14, TOOTH DEVELOPMENT -------------------------------------------------------
90
2
VERTEBRATE DEVELOPMENT - BIOL 4410 LECTURE and LAB
FALL 2016 - LECTURE AND LAB TOPICS, STUDY ASSIGNMENTS
C - Carlson (6th edition), S - Schoenwolfe (7th edition), D - Digital Lab Manual
(If you have a different edition of the text, the required page numbers may be different.)
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Aug 17 W
Class orientation, drops and adds, lab switches
Introduction, Developmental biology as a science
Gametogenesis I: Gametes, where do they come from.
C: pp. 1-56, pp. 57-74
W/Th
NO LAB TODAY!
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-----------------------------------------------------------------------------------------------------------Aug 19 F
Finish Introduction, Developmental biology as a science
Gametogenesis I: Gametes, where do they come from.
C: pp. 1-56, pp. 57-74
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Aug 22 M
Gametogenesis I: Gametes, where do they come from
C: pp. 57-74
M/T
ATTENDANCE AT THIS LAB IS REQUIRED!!!!
Lab: Equipment assignments. Use of microscope.
D: Introductory materials, Approaches to learning
Routine methods of Microtechnique
Microscopy: Use of the Microscope
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-----------------------------------------------------------------------------------------------------------Aug 24 W
Gametogenesis II: Spermatogenesis
C: pp. 75-93
W/Th
ATTENDANCE AT THIS LAB IS REQUIRED!!!!
Lab: Histological sections, a 2-dimensional view of 3-dimensions.
Reproductive organs. Tray #1 & 2.
D: Developmental Events and Mechanisms, General Background
Information, Gametogenesis, Fertilization
M: pp. 1-15, 74-77, 126-129
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-----------------------------------------------------------------------------------------------------------Aug 26 F
Gametogenesis II: Spermatogenesis
.
C: pp. 75-93
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3
Aug 29
M
Gametogenesis II: Finish Spermatogenesis. Start Oogenesis
C: pp. 75-93 C: pp. 94-120
M/T
Lab: Starfish development. Tray #3. Quiz 1
D: Starfish Development, Descriptive Text
M: pp. 50-56
FIRST LAB QUIZ TODAY!
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Aug 31 W
Gametogenesis III: Oogenesis
C: pp. 94-120
W/T h
Lab: Early frog development. Tray #4. Quiz 2
D: Amphibian Development, Early Frog Development, Descriptive Text
M: pp. 78, 81-96
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-----------------------------------------------------------------------------------------------------------Sept 2 F
Gametogenesis III: Oogenesis
C: pp. 94-120
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-----------------------------------------------------------------------------------------------------------Sept 5 M
LABOR DAY HOLIDAY
15th day of classes tomorrow
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-----------------------------------------------------------------------------------------------------------Sept 7 W
Finish Fertilization,
C: pp. 121-142
W/Th
Lab: 4mm Frog tadpole. Tray #5 Quiz 3
D: Amphibian Development, 4mm Frog Tadpole,
Descriptive Text for Wholemount and Transverse sections
M: 97-105
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-----------------------------------------------------------------------------------------------------------Sept 9 F
Fertilization
C: pp. 121-142
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-----------------------------------------------------------------------------------------------------------Sept 12 M
Cleavage.
C: pp. 143-150, 151 - 188
M/T
Lab: Frog development, 4-7 mm, Tray #5. Quiz 4
D: Amphibian Development, 7mm Frog Tadpole,
Descriptive Text for Wholemount and Transverse sections
M: pp. 97-105, 106-116
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4
Sept 14 W
Cleavage.
C: pp. 143-150, 151 - 188
.
W/Th
Lab: Frog development, 4-7 mm, Tray #5. Quiz 5
D: Amphibian Development, 7mm Frog Tadpole,
Descriptive Text for Wholemount and Transverse sections
M: pp. 97-105, 106-116
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Sept 16 F
Cleavage.
C: pp. 143-150, 151 - 188
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Sept 19 M
Gastrulation.
C: pp. 189-226
M/T
Lab: Frog development, 10mm. Tray #7. Quiz 6
D: Developmental Events and Mechanisms, Cleavage
D: Amphibian Development, 10mm Frog Tadpole,
Descriptive Text for Wholemount and Transverse sections
M: pp. 117-123
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Sept 21 W
FIRST LECTURE EXAM (through Monday's lecture)
W/Th
Lab: Frog development, 10mm. Tray #7. Quiz 7
D: Developmental Events and Mechanisms, Cleavage
D: Amphibian Development, 10mm Frog Tadpole,
Descriptive Text for Wholemount and Transverse sections
M: pp. 117-123
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Sept 23 F
Gastrulation. C: pp. 189-226
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Sept 26 M
Gastrulation.
C: pp. 189-226
M/T
Lab: Chicken development, 18 hr, 24 hr. (4 somite) Tray #8. Quiz 8
D: Developmental Events and Mechanisms, Gastrulation
D: Avian Development, Major Events in Early Avian Development
Descriptive Text
D: Avian Development, 18 hr and 24 hr chick embryo
Descriptive Text for 18 hr and 24 hr embryos,
Wholemounts and Transverse sections
M: pp. 131-134, M: pp. 134-144
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5
Sept 28 W
Neurulation and Induction
Read information in Lecture Handout
W/Th
Lab: FIRST LAB EXAM (through 24 hr chick).
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Sept 30 F
Neurulation and Induction
Read information in Lecture Handout
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 3 M
Embryonic adaptations (membranes).
C: pp. 255-273 (birds & mammals), 274-290 (primate, human)
M/T
Lab: Chicken development 33 hr. (12-13 somite) Tray #9. Quiz 9
D: Developmental Events and Mechanisms, Neurulation
D: Avian Development, 33 hr Chick Embryo
Descriptive Text for Wholemount and Transverse Sections
M: pp. 145-152
Your lab notebook completed through the 10mm frog is due at beginning of
your lab!
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 5 W
Embryonic adaptations (membranes).
C: pp. 255-273 (birds & mammals), 274-290 (primate, human)
W/Th
Lab: Chicken development 48 hr. Tray #10. Quiz 10
D: Avian development, 48 hr Chicken Embryo
Descriptive Text for Wholemount and transverse sections
M: pp. 153-170
MID-SEMESTER IS TODAY, YOU MUST HAVE PERMISSION FROM THE DEAN'S
OFFICE TO DROP AFTER TODAY!
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 7 F
Finish Emrbyonic adaptations,
C: pp. 255-273 (birds & mammals), 274-290 (primate, human)
C: pp. 311-324
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 10 M
Differentiation
C: pp. 311-324
M/T
Lab: Chicken development 48 hr. Tray #10. Quiz 11
D: Avian development, 48 hr Chicken Embryo
Descriptive Text for Wholemount and transverse sections
M: pp. 153-170)
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-----------------------------------------------------------------------------------------------------------6
Oct 12 W
Differentiation
C: pp. 311-324
W/T h
Lab: Chicken development 72 hr. Tray #11. Quiz 12
D: Developmental Events and Mechanisms, Morphogenesis
D: Avian development, 72 hr Chicken Embryo
Descriptive Text for Wholemount and transverse sections
M: pp. 171-189
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 14 F
FALL BREAK!
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 17 M
Early human (mammalian) development.
C: pp. 274-310
M/T
Lab: Chicken development 72 hr. Tray #11. Quiz 13
D: Avian development, 72 hr Chicken Embryo
Descriptive Text for Wholemount and transverse sections
M: pp. 171-189
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 19 W
Organogenesis (Intro + Ectoderm). Nervous system.
C: pp. 227-239, 427-484
W/Th
Lab: Chicken development 96 hr. Tray #12. Quiz 14
D: Avian development, 96 hr Chicken Embryo
Descriptive Text for Wholemount and transverse sections
M: pp. 190-195)
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 21 F
Organogenesis (ectoderm 2). Nervous system I.
C: pp. 227-239, 427-484
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 24 M
Organogenesis (ectoderm 3). Nervous system II.
C: pp. 227-239, 427-484
M/T
Lab: Chicken development 96 hr. Tray #12. Quiz 15
D: Avian development, 96 hr Chicken Embryo
Descriptive Text for Wholemount and transverse sections
M: pp. 190-195
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Oct 26 W
SECOND LECTURE EXAM (through Monday's lecture)
W/Th
Lab: 6mm pig. Tray #13. Quiz 16
Descriptive text for transverse sections
M: pp. 198-237
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-----------------------------------------------------------------------------------------------------------7
Oct 28 F
Organogenesis (Mesoderm 1). Musculo-skeletal system I
C: 311-353
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------OCT 31 M
Organogenesis (Mesoderm 1). Musculo-skeletal system I
C: 311-353
M/T
Lab: 6mm pig. Tray #13. Quiz 17
Descriptive text for transverse sections
M: pp. 198-237
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Nov 2 W
Organogenesis (mesoderm 2). Circulatory system I - Origin
C: pp. 607-644
C: pp. 619-644
W/Th
Lab: 6mm pig. Tray #13. Quiz 18
Descriptive text for transverse sections
M: pp. 198-237
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Nov 4 F
Organogenesis (mesoderm 2). Circulatory system II - Arteries
C: pp. 607-644
C: pp. 619-644
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Nov 7 M
Organogenesis (mesoderm 2). Circulatory system II - Arteries/veins
C: pp. 607-644
C: pp. 619-644
M/T
Lab: 10mm pig. Tray #14 & #15-1. Quiz 19
M: pp. 201-237
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Nov 9 W
Organogenesis (mesoderm 2). Circulatory system II - Veins
C: pp. 607-644
C: pp. 619-644
W/Th
10mm pig. Tray #14 & #15-1. Quiz 20
M: pp. 201-237
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Nov 11 F
Organogenesis (mesoderm 3). Urogenital system II
C: pp. 569-606
________________________________________________________________________
------------------------------------------------------------------------------------------------------------
8
Nov 14 M
Organogenesis (mesoderm 3). Urogenital system I
C: pp. 569-606
M/T
Tooth Development, Tray #15-2, Quiz 21
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Nov 16 W
Organogenesis (mesoderm 3). Urogenital system III
C: pp. 569-606
W/Th
LAB NOTEBOOKS DUE immediately before the exam!
LAB FINAL EXAM - comprehensive with emphasis on chick &
pig. Lab Clean-up. Turn in microscopes and slides.
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Nov 18 F
Organogenesis (endoderm). Face, Visceral arches, lips, tongue, teeth
C: pp. 513-526, 537-546
________________________________________________________________________
------------------------------------------------------------------------------------------------------------
Nov
21-25
Thanksgiving Vacation
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-----------------------------------------------------------------------------------------------------------Nov 28 M
Organogenesis (endoderm). Face, Visceral arches, lips, tongue, teeth
C: pp. 513-526, 537-546
M/T
GO OVER LAB FINAL EXAM. QUIZ AVERAGES WILL BE
RETURNED
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Nov. 30 W
Organogenesis (endoderm). Face, Visceral arches, lips, tongue, teeth
C: pp. 513-526, 537-546
W/Th
No lab today! (-;{
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Dec 2 F
Organogenesis (endoderm). Face, Visceral arches, lips, tongue, teeth
LAST DAY OF CLASSES
C: pp. 513-526, 537-546
________________________________________________________________________
-----------------------------------------------------------------------------------------------------------Dec
FINAL LECTURE EXAM (through last lecture, COMPREHENSIVE) at
8:00 A.M. - 9:30 A.M. in lecture rooms (SCC 115/122).
________________________________________________________________________
------------------------------------------------------------------------------------------------------------
9
COURSE POLICIES:
Disabilities: If you have a disability that requires special consideration, please talk to me during the first
two weeks of classes so that arrangements to accommodate your needs can be made.
Equipment Responsibilities: Students will be responsible for keys and laboratory equipment assigned to
them. Failure to check in keys and all lab equipment at the end of the semester in good condition will
result in an Incomplete course grade until the matter is resolved.
Attendance:
Attendance is required at the first 2 lab sessions.
Attendance is required for lecture and lab exams/quizzes.
Absence will be condoned only if an acceptable, verifiable, written excuse is provided. Absence without
an acceptable excuse will result in a grade of zero (0) for the exam missed. Make-up examinations will be
given as soon as practical. No make-ups are given on lab quizzes (see below). No unannounced quizzes
will be given.
Lab Quizzes: Starting with the second lab, a quiz will be given immediately before the introductory
lecture to the lab. Quizzes will cover the material worked on in the previous lab. There will be no make-up
quizzes. If you can provide an acceptable, verifiable, written excuse for missing a quiz, that quiz will not
be included in the final calculation of your cumulative quiz grade. Quizzes will not be given on lab exam
days; however, quizzes WILL be given on lecture exam days.
Academic Honesty: Cheating is defined, and rules regarding the reporting of honesty cases are
described, in the Tiger Cub. Cheating, including plagiarism of class work from the efforts of students
who took Vertebrate Embryology in previous semesters, is a very serious offense and will be dealt
with by the Auburn University Academic Honesty Committee. Please note that I do not allow
students to keep my exams. Thus, there should be no copies of my exams available to you. If some
copies of my exams have somehow escaped my “grip”, they have been obtained by illicit means and
using such exams to study is also cheating.
Honesty and the digital age: The digital age brings with it new problems in regard to academic
honesty. Items such as smartphone cameras, “spy” pens, lapel and eyeglass cameras, and other sorts
of recording devices are now available. Use of such devices to acquire copies of exams or exam
questions is a form of cheating. Similarly, using materials acquired by such devices to study for
exams is also cheating. So, please do not use such devices to illicitly copy exam materials in this
course and do not use materials acquired by such devices to study for exams. If you are found guilty
of copying exams with a digital device, you will receive an automatic F in the course and it will be
recommended to the Academic Honesty Committee that you be suspended.
NOTE! When graded exams are returned for your examination during class, all digital devices must be
put away either in your backpack or pocket. If we see you have a cell phone or other digital device in your
hand or on your desk/bench top while we are going over exams, 10 pts (one letter grade) will be
subtracted from your exam score. No excuses will be accepted for this sort of infraction, so please be sure
that all digital devices are in pocket or backpack prior to exams being returned.
10
LABORATORY REQUIREMENTS/INFORMATION:
!!ATTENDANCE AT THE FIRST TWO LABS IS REQUIRED. IF YOU FAIL TO ATTEND YOU
WILL LOSE 1 POINT ON YOUR FINAL CLASS AVERAGE FOR EACH LAB MISSED!!
Laboratory assignments in this Vertebrate Development course, as in most others, require an intensive
study of histological sections of fixed tissues (gonadal and embryonic). In order to do well in the
laboratory portion of this course it will be necessary to devote considerable time to the examination of
your microscope slides. For most students, this will mean study time outside the scheduled laboratory
periods if high grades are desired on the lab exams. To facilitate such study, access to the lab is controlled
by a card-swipe lock, i.e. your student ID card can be used to open the lab door. The rules for lab use will
be given to you at the first lab. Be there!!!!!
A list of required identifications will be handed out for each slide, or set of slides, used in the course. You
are to locate the listed “structures” on your slides and relate them to their position, function, and shape in
the embryo or tissue where applicable. It is important to know,
1) what these structures are,
2) in some cases, what they will become or what they were,
3) what germ layer they are derived from
4) and what they do in the embryo and/or adult.
Some of this information will be obvious, some will be presented in lecture or lab, and some will be found
in your reading assignments.
LAB EXAMS:
Two lab exams will be given during the semester. These exams will cover the material indicated in the
class schedule. The second lab exam is comprehensive. Examples of Lab Exam and quiz questions are
given starting on page 17 of this handout.
CHECK THE SYLLABUS AND NOTE THE LAB EXAM DATES!! IF YOU PLANS ON THOSE
DATES THAT WOULD CAUSE YOU TO MISS THE LAB EXAM, CHANGE THEM NOW! IF
YOU HAVE SOME EVENT DURING THE DAYS DIRECTLY PRECEEDING A LAB EXAM,
PLAN ACCORDINGLY! There are very few excuses that I will accept for missing a lab exam on its
scheduled date.
LAB QUIZZES:
There will be a short quiz given during each lab period starting with the second lab. Quizzes will cover the
material worked on in the previous lab. Quizzes will continue to be given at every subsequent lab except
those during which a lab exam is given. There will be no make-up quizzes. If you can provide an
acceptable, verifiable, written excuse for missing a quiz, that quiz will not be included in the final
calculation of your cumulative quiz grade. Please note that quizzes WILL be given on "lecture exam"
days.
Each quiz will be worth 4 points and will consist of two identifications of embryonic structures/tissues
from slides projected on the screen at the front of the class room and 2 short answer questions concerned
with the structures/tissues you identified. At the end of the semester your quiz average (%) will be
calculated as follows.
Quiz Average Example: (For an example where 10 quizzes are given)
Total points received for all your quizzes - 34
Total points possible
- 40
Quiz average = (34/40) X 100 = 85%
Examples of Lab exam and quiz questions are given starting on page 17 of this handout
11
LAB NOTEBOOK:
Each student will prepare a lab notebook that summarizes their work in the laboratory portion of this
course. Specific requirements for this notebook are given in the Laboratory Handout Packet available on
the class web site. PLEASE NOTE: Lab notebooks must be turned in for grading on the two dates
indicated in the syllabus schedule. On those days, the lab notebooks are due at the beginning of your
lab period. In order to receive a grade other than "0" for a lab notebook turned in after this time, you must
have an acceptable, written, verifiable excuse for your failure to turn the notebook in on time. Your final
Lab Notebook grade will be the rounded average of the two grades you receive for the notebook.
PREPARATION OF LAB NOTEBOOK:
EACH STUDENT WILL PREPARE A LAB NOTEBOOK THAT SUMMARIZES THEIR WORK IN
THE LABORATORY PORTION OF THE COURSE.
YOUR LAB NOTEBOOK SHOULD BE ARRANGED IN THE FOLLOWING SECTIONS AND
CHAPTERS. EACH CHAPTER WILL REPRESENT ONE OF THE ORGAN SYSTEMS/EMBRYONIC
STAGES YOU HAVE EXAMINED.
SECTIONS AND CHAPTERS:
TABLE OF CONTENTS
INTRODUCTORY MATERIAL
I.
REPRODUCTIVE ORGANS
II.
STARFISH DEVELOPMENT
FROG DEVELOPMENT
III.
EARLY FROG DEVELOPMENT
IV.
4 mm FROG
V.
7 mm FROG
VI.
10 mm FROG
CHICKEN DEVELOPMENT
VII.
EARLY AND 18-24 hr CHICK
VIII.
33 hr CHICK
IX.
48 hr CHICK
X.
72 hr CHICK
XI.
96 hr CHICK
PIG DEVELOPMENT
XII.
6 mm PIG
XIII.
10 mm PIG
FOR THE EL PERFECTO NOTEBOOK
A GOOD TABLE OF CONTENTS
EACH CHAPTER OF THE PERFECT LAB NOTEBOOK WILL CONTAIN THE FOLLOWING
ITEMS IN THE FOLLOWING ORDER FOR EACH ORGANISM (i.e., Reproductive organs,
Starfish, Frog, Chicken and Pig):
12
1. DETAILED LAB LECTURE NOTES FOR ALL LAB LECTURES THAT WERE CONCERNED
WITH THAT ORGAN SYSTEM/EMBRYONIC STAGE.
2. ALL QUIZZES
3. ALL LABELED DRAWINGS OF SECTIONS SHOWING EVERY STRUCTURE YOU ARE
SUPPOSED TO BE ABLE TO IDENTIFY FOR THAT ORGAN SYSTEM/EMBRYONIC STAGE.
4. A TABLE IDENTIFYING THE GERM LAYER ORIGIN OF EACH TISSUE/ORGAN/STRUCTURE
TO BE IDENTIFIED, WHAT IT WILL FORM, AND WHAT ITS EVENTUAL FUNCTION WILL
BE. (This is not required for Reproductive Organs or Starfish.)
DETERMINATION OF LAB NOTEBOOK GRADES:
See the Lab Notebook grading sheets available in the Lab Notebook section on the course web site.
THE LAB NOTEBOOK WILL REPRESENT 20% OF YOUR LAB GRADE.
13
LAB NOTEBOOK - FREQUENTLY ASKED QUESTIONS
(Prepared by Kyle Barrett, 2004; updated by Maria Mays, 2012)
Q. Does it matter how I organize my notebook?
A. Yes. When you're putting the notebook together, please organize items as described in your lab
packet. This means you'll have the notebook divided into sections for the notes, drawings, quizzes,
and germ layer charts. Within those sections, you'll have your notebook organized based on the
organism and stage of development. You DO NOT need to produce a germ layer chart for each
stage. Only for each organism (i.e., the frog, chick, and pig).
Q. How should the notebook be bound?
A. The contents of your notebook should go into a three-ring binder.
Q. Do my table of contents need to have page numbers?
A. No. You do not have to number each page in the notebook and you do not need to have page
numbers in the table of contents. Just list the order you have placed things in the notebook.
Q. How many drawings are required for a section?
A. There is no required number of drawings. You need to have as many drawings as it takes for
you to be able to label the structures listed in the ID lists in your course lab packet. Often, from a
single drawing you can label a dozen structures or more. Sometimes, you may have to make a
single sketch just to label one item. If this is the case, partial sketches are fine (i.e., you don't have
to draw the entire embryo; just show us enough so we can tell where your drawing is coming from).
Q. Do I have to label every single term on the list for a particular organism and stage?
A. No. Any time a term is new to an embryo you must label it on a drawing (new terms will
appear in italics). Often times terms will continue to appear on the list after they have first
developed. For example, you will see the term prosencephalon show up when you are studying the
24 hr chick. Because it is the first time you've seen the term for the chick, you'll want to label it.
The term will continue to show up on future chick lists (48 hrs, 72 hrs, 96 hrs). You do not have to
re-label the structure for these stages. For each type of embryo you will also be assigned 1 or 2
organ systems that you have to continue drawing (see the included full list of what you have to
draw). Also, even if you have already labeled a term from a previous type of embryo (e.g. frog),
you must draw and label it again if the same term applies to a new embryo (e.g. chicken). If in
doubt about whether or not you should draw and label something, just ask.
Q. But I can't draw very well, will you take off points for that?
A. Nope. Just do the best you can. Even if you are not very artistic try to be neat (that helps us
look at your pictures and give you all the points you deserve).
Q. Should I include my course packet in the notebook?
A. No, you keep it - we already have a copy.
14
Q. What sort of paper/pencils should I use for my drawings?
A. Plain white paper is preferred, but not required. Pencils are preferred over pen, but again, not
required. If you use a pen that is very inky and bleeds through the paper (even very faintly), we
ask that you draw only on one side of the paper.
Q. Mitosis, meiosis, and other processes, not structures, are on the list. How do I draw these?
A. Any time a process shows up on the list (they rarely do) you should just sketch a diagram of it.
For example, with meiosis, you could draw a circle representing the cell and lines within that circle
representing chromosomes. Using these symbols and the appropriate labels you should be able to
show what happens during the process of meiosis.
Q. In the section on the frog, the 4-7 mm stages are listed together. Will one set of drawings for
these stages be OK?
A. No. You have separate slides for the 4 and 7 mm frog and you should make separate drawings.
However, see the question "Do I have to label every single term..." for more on this.
Q. What's a Germ Layer Chart?
A. The Germ Layer Chart is a table that contains germ layer, fate, and function information on the
structures on your ID lists in the course lab packet. You must make three of them, one each for the
frog, chicken, and pig. The germ layer charts must be typed. Here's an example of what it should
look like:
Structure/Tissue
Archenteron
Myotome
Otic vesicle
Prosencephalon
Germ Layer
Endoderm
Mesoderm
Non-neural Ectoderm
Neural Ectoderm
What if forms
Embryonic Gut
Skeletal Muscle
Inner Ear
Forebrain
Function or System
Digestion
Movement
Sensory-Auditory
Central Nervous System
Q. How will my notebook be graded?
A. See the lab notebook grading sheets.
Q. If I encase the pages of my notebook in plastic cover sheets will my TAs be impressed with my
initiative and give me a better score?
A. No. Please don't use plastic cover sheets for any portion of your notebook. They make it
difficult to write notes/make corrections on your pages.
15
POSSIBLY USEFUL STUDY HINTS:
You may find it useful to bring Red, Yellow, Orange, Blue, and Green colored pencils to lab and lecture. I
will be drawing colored figures on the board that indicate cells that will give rise to, or tissues that are
derived from, the various germ layers. Blue - ectoderm, Red - mesoderm, Green - chordamesoderm (a
special type of mesoderm), Yellow - endoderm, Orange - yolk.
A glossary is available at the end of your lab manual (Wright, 2005). I strongly recommend that you make
maximum use of this study aids.
Other study aids available in both lab texts are the various figures in each chapter. These can be used in a
number of ways,
1. As a comparative aid in studying your slides.
2. As an aid in reconstructing a 3-dimensional image of an embryo in your mind’s eye.
3. As an aid in relating various organs and structures to each other.
4. As a means of identifying specific organs and structures.
5. As a means of organizing organs and tissues into groups, i.e. those derived from ectoderm, mesoderm,
or endoderm; or those associated with a specific organ system, for instance the digestive tract. In the case
of organs and tissues derived from ectoderm, mesoderm, or endoderm, it will be helpful to draw and color
in some of the figures with the appropriate colors corresponding to these germ layers.
BLUE - ectoderm
RED - mesoderm YELLOW - endoderm
Notochord, which is derived from chordamesoderm, is colored GREEN to signify its special effects on
development. Yolk, which is present in large amounts in frog and particularly chicken eggs, is colored
ORANGE.
6. As a means of testing your knowledge by labeling specific organs, tissues, and structures in figs. where
they are not labeled.
16
LAB EXAM AND QUIZ SAMPLE QUESTIONS:
The following are examples of the sort of questions that will be asked on the laboratory exams and
quizzes.
LABORATORY EXAMS (Sec. I): On laboratory exams, the first group of questions will be concerned
with structures I will point out on projected slides.
e.g.
1.The lab instructor points to the Graafian follicle of a mammal and asks,
What structure is this?
or
Give two synonymous names for this structure.
answer - Graafian follicle, tertiary ovarian follicle
2. The lab instructor points to the spermatogonial cells in a lobe of the grasshopper testis and asks,
What are these cells called?
answer - spermatogonia
or
What function do these cells perform?
answer - give rise to primary spermatocytes
or
- they function as stem cells for the male
germ cell line
3. The lab instructor points to the chordamesoderm of an early frog embryo and asks,
What embryonic structure will form from these cells?
answer - notochord
or
What characteristic embryonic structure in the frog is involved in the internalization of these cells?
answer - dorsal lip of the blastopore
17
LABORATORY EXAMS (Sec. II): The second group of questions on laboratory exams will involve
identification of specific structures or processes using your microscope and slide set. You will locate the
item indicated on the appropriate slide and put the very tip of the pointer directly on/over that item. Once
you have done this, you will raise your hand a lab instructor will come to your place, check the
identification, and mark it either right (+) or wrong (0). After each identification will be a question about
the structure or process that requires a short, simple, written answer (usually one or two words).
e.g.
Identify the following and answer the question after each identification.
1. primary spermatocyte
In terms of chromosome number, what is the ploidy of this cell immediately following the mitotic division
of the spermatogonial cell that gave rise to it?
answer - diploid
or
What type of cell immediately preceded the formation of this cell?
answer - type B spermatogonium
2. zona pellucida
Is this structure cellular or acellular?
answer - acellular
or
What is this structure composed of?
answer - glycoproteins
3. liver diverticulum
Name an adult organ will form from the cells surrounding this diverticulum?
answer - liver or gall bladder
or
What cavity within the 4 mm frog is the lumen of this structure continuous with?
answer - foregut or pharynx
Finally, when you are making identifications on your slides,
THE VERY TIP OF YOUR MICROSCOPE POINTER MUST BE DIRECTLY OVER (“ON”) THE
STRUCTURE TO BE IDENTIFIED.
ALMOST DOESN’T COUNT!
18
LABORATORY QUIZZES: Quizzes will use slides that are projected on the screen in front of the
classroom. Each quiz will consist of either two, 2-part questions or 4 one part questions and be worth a
total of 4 points. For the 2-part questions, the lab instructor will first point to a tissue or structure on the
screen and ask you to identify it. The second part will consist of a short answer question about some
aspect of the tissue or structure you identified. One part questions will involve identifying a structure or
answering some question about it.
1. a. The lab instructor points to a spermatid on a projection of a grasshopper testis slide and asks, "Give a
specific name for this cell".
answer - spermatid
b. The lab instructor asks "What is the name of the process that results in the development of a
spermatid into a mature spermatozoon?"
answer - spermiogenesis or spermateleosis or spermatozoon metamorphosis
(these are 3 different names for the same process, i.e. synonyms)
2. a. The lab instructor points to the notochord on a projection of a frog tadpole transverse section and says
"Give the specific name for this structure".
answer - notochord
b. The lab instructor says "What germ layer is this structure derived from?"
answer - mesoderm or chordamesoderm
(if the lab instructor had said "What specific germ layer is this structure derived from?", then only
"chordamesoderm" would have received full credit.)
19
Lab Handout 1A
VERTEBRATE DEVELOPMENT BIOL 4410
LAB ORIENTATION
LABORATORY ORIENTATION:
SEAT ASSIGNMENTS
Remain the same for entire semester once assignment is made. Seat assignment corresponds to equipment
assignment.
EQUIPMENT ASSIGNMENT
You will be assigned one set of microscope slides of histological sectioned and stained embryos and
tissues. A binocular compound microscope with electric light source will be assigned and kept in the
locked cabinet adjacent to your seat. You are responsible for these items and they should be returned in
good condition at the end of the course. Charges will be made for lost or damaged equipment.
EXTRACURRICULAR. LAB USE
Arrangements have been made so that it will be possible for you to use the 24/7, except on football
weekends. This will be discussed further in lab.
Entrance to the SCC building after 5 PM or on weekends is accomplished by using your ID card in the
"swipe" lock of the door closest to the class lab or in the middle of the building on the Chemistry building
side. DO NOT PROP THE OUTSIDE OR LAB DOORS OPEN! IF THIS IS DONE THE CLASS
WILL LOSE ITS 24/7 PRIVILAGES.
During lab use outside of regular class time, the last person to leave the lab is responsible for making sure
the lab door is locked. Be sure to actually test the door by trying to turn the door knob and pulling on the
door. Sometimes, for whatever reason, the lock mechanism fails to function.
If you leave the lab for any reason (going to the rest room, a cigarette break, to buy a coke, etc.) and there
is no one else in the lab, then the door must be locked while you are gone. NO EXCEPTIONS.
Use of the lab outside regular lab time will continue only so long as everyone observes the rules set down
above. IF ONE PERSON BECOMES LAX, THEN THIS SORT OF LAB USE WILL BE CURTAILED
FOR EVERYONE. If you are the cause of this, I suspect your classmates will not be too happy with you.
20
LAB INTRODUCTION:
1. THE FIRST LAB WILL BE CONCERNED WITH INTRODUCTORY MATERIAL. IF YOU
CANNOT ATTEND BECAUSE OF SCHEDULING DIFFICULTIES, YOU MUST ARRANGE TO
SEE ONE OF THE TAs ABOUT MICROSCOPE USE BEFORE YOU USE YOUR MICROSCOPE.
NO EXCEPTIONS!
2. CHAIRS UNDER BENCH AT END OF PERIOD.
3. MICROSCOPES AND SLIDES IN DRAWER OR CABINET AND LOCKED WHEN YOU ARE
THROUGH USING THEM.
4. LAB USE DURING TIMES OTHER THAN SCHEDULED LAB PERIODS. THIS WILL ONLY
WORK AS LONG AS EVERYONE RESPECTS RULES CONCERNING THIS SORT OF LAB USE.
BE SURE DOOR TO LAB IS LOCKED IF YOU LEAVE ROOM AND NO ONE ELSE IS IN IT.
DO NOT PROP THE OUTSIDE OR LAB DOORS OPEN! IF THIS IS DONE THE CLASS
WILL LOSE ITS 24/7 PRIVILAGES.
5. IT IS TO YOUR ADVANTAGE TO ATTEND SCHEDULED LABS. THAT IS THE TIME
SOMEONE WILL BE PRESENT TO ANSWER QUESTIONS CONCERNING YOUR SLIDES. IN
ADDITION, YOU WILL WANT TO BE PRESENT FOR THE LAB QUIZZES GIVEN DURING
EACH LAB PERIOD. YOUR SCORES ON THESE QUIZZES WILL DETERMINE 20% OF YOUR
LAB GRADE. EVERYONE MUST BE IN LAB ON THE DATES OF SCHEDULED LAB EXAMS.
NO EXCEPTIONS!
6. LAB QUIZZES WILL BE GIVEN DURING EVERY LAB PERIOD STARTING WITH THE
SECOND LAB OF THE SEMESTER. THESE QUIZZES WILL DETERMINE 20% OF YOUR LAB
GRADE. SEE p. 19 FOR A BRIEF DESCRIPTION OF QUIZZES. SEE p. 19 OF THIS HANDOUT
FOR EXAMPLES OF THE SORTS OF QUESTIONS THAT WILL BE ASKED ON LAB QUIZZES.
7. LAB EXAMS ARE PRACTICAL AND OBJECTIVE. YOU WILL HAVE TO MAKE
IDENTIFICATIONS ON YOUR SLIDES WHICH I WILL CHECK. IN ADDITION, THERE WILL
BE A SHORT ANSWER QUESTION ABOUT THE STRUCTURE IDENTIFIED. YOU WILL ALSO
HAVE TO IDENTIFY AND ANSWER QUESTIONS ABOUT TISSUES AND STRUCTURES I
PROJECT ON THE SCREEN. DO NOT ASK TO BE EXCUSED FROM LAB EXAMS UNLESS
YOU ARE TRULY SICK OR HAVE SOME SORT OF REAL EMERGENCY. IF YOU ARE SICK
YOU WILL NEED TO PROVIDE A DOCTOR'S EXCUSE THAT SPECIFICALLY STATES
YOU WERE TOO SICK TO ATTEND THE LAB EXAM. CLINIC EXCUSES THAT SIMPLY
SAY YOU VISITED THE CLINIC WILL NOT BE ACCEPTED. IF YOU MISS AN EXAM
WITHOUT AN ACCEPTABLE EXCUSE YOU WILL RECEIVE A ZERO (0) FOR THAT EXAM.
SEE pp. 17 - 18 OF THIS HANDOUT FOR EXAMPLES OF THE SORTS OF QUESTIONS ASKED
ON LAB EXAMS.
8. FINALLY, YOU ARE RESPONSIBLE FOR YOUR MICROSCOPE AND SLIDES. SO BE
CAREFUL WHEN USING THEM.
IMPORTANT THINGS TO REMEMBER WHEN USING THE EMBRYOLOGY LAB
1. When you remove your microscope from its cabinet or return it to the cabinet, use BOTH hands and
take care not to bump the mechanical stage controls against the sides of the cabinet.
21
2. WHEN CLEANING LENSES, USE ONLY NEW, VIRGIN, LENS PAPER OR Q-TIPS! Once
you have wiped a lens never re-use the Q-tip or lens paper. Throw it away and get out a new one. Lens
paper and Q-tips are cheap, objectives, oculars and other lenses are very expensive.
3. WHENEVER YOU CHANGE SLIDES OR LOSE FOCUS ON THE SLIDE YOU ARE VIEWING,
ALWAYS RE-START YOUR VIEWING BY FOCUSING WITH THE 4X OR 10X OBJECTIVE!
Then move back to higher power objectives focusing with each one before moving to the next highest
power.
4. IF YOU ARE THE LAST PERSON TO LEAVE THE LAB AT TIMES OTHER THAN
REGULAR CLASS SESSIONS, BE SURE THE DOOR IS CLOSED AND LOCKED WHEN
YOU LEAVE!
22
Lab Handout 1B VERTEBRATE DEVELOPMENT BIOL 4410
MICROSCOPY
USE OF THE COMPOUND MICROSCOPE
HOW TO HANDLE A MICROSCOPE:
A compound microscope should be treated as a VERY, VERY, VERY fragile piece of equipment.
1. Adjustments should be made gently and with finesse.
2. ALWAYS use BOTH HANDS when picking the microscope up and moving it.
3. When focusing on a slide, ALWAYS start with either the 4X or 10X objective. Once you have the
object in focus, then switch to the next higher power objective. Re-focus on the image and then switch
to the next highest power. Etc. NEVER advance more than one objective before focusing.
4. Use ONLY the fine focus control when focusing for higher power objectives (20X, 40X, 100X). The
coarse focus control is too coarse for focusing with these objectives. Objectives are fragile and must
not be rammed into slides.
5. If an objective or ocular needs to be cleaned use the Q-tips and breath moisture or the methanol
available on the front desk in the lab. THE FOLLOWING NOTES ON CLEANING ARE VERY
IMPORTANT!
a. USE ONLY NEW, UN-USED Q-TIPS FOR CLEANING. Even Q-tips that have only been used once
may have dirt on them that could scratch a lens or contaminate the methanol and cause scratches when
the now dirty methanol is used for cleaning in the future.
b. WHEN LENS PAPER IS USED TO CLEAN OBJECTIVES OR OCULARS, USE A NEW, CLEAN
SECTION OF THE PAPER EACH TIME YOU WIPE THE LENS SURFACE.
c. NEVER SAVE USED LENS PAPER OR Q-TIPS. THEY SHOULD NEVER BE RE-USED ON ANY
OF THE LENSES.
d. IF YOU RUN INTO A PARTICULARLY TENACIOUS BIT OF DIRT ON A LENS, SEE THE
CLASS INSTRUCTOR ABOUT REMOVING IT RATHER THAN TRYING TO DO IT
YOURSELF.WITH THESE THINGS IN MIND LET’S RUN THROUGH THE USE OF THE
MICROSCOPE WITH AN EXAMPLE SLIDE.
INITIAL PROCEDURES:
1. REMOVE PLASTIC COVER AND USING BOTH HANDS, REMOVE YOUR MICROSCOPE
FROM ITS CABINET AND PLACE IT ON THE LAB BENCH IN FRONT OF YOU. PUT PLASTIC
COVER IN CABINET.
2. PLUG THE POWER CORD INTO THE BENCH SOCKET AND TURN ON THE LIGHT.
3. MAKE SURE THAT THE 10X OBJECTIVE IS IN POSITION OVER THE VIEWING AREA. THE
OBJECTIVE SHOULD BE POSITIONED ABOUT 1/4” - 3/8” ABOVE THE STAGE.
23
4. PLACE A SLIDE ON THE MICROSCOPE STAGE SUCH THAT THE PORTION OF THE SLIDE
YOU WANT TO VIEW IS UNDER THE OBJECTIVE.
5. FOCUS ON SPECIMEN, FIRST USING THE COARSE AND THEN THE FINE FOCUS
CONTROLS. YOU MAY HAVE TO MOVE THE SLIDE AROUND ON THE STAGE OF THE
MICROSCOPE TO BRING THE SPECIMEN INTO THE VIEWING AREA.
ADJUST THE POSITION OF THE OCULARS (the interocular distance) SO THAT A SINGLE IMAGE
CAN BE SEEN WHEN LOOKING THROUGH BOTH OCULARS AT THE SAME TIME.
If your eyes are too close set or far apart for the intraocular distance to be adjusted properly, you will have
to use your microscope as a monocular instrument (i.e. look through one eyepiece with one eye). If you do
this, it is important to keep both eyes open in order to avoid eyestrain. With a little practice, you should be
able to train yourself to “see” only what is being viewed with the microscope, and ignore whatever the
other eye is seeing. If you can’t do this, a trick that works is to buy a cheap pair of sunglasses, knock out
the dark lenses and put a piece of cardboard in the lenses over the eye that you don’t look through the
microscope with. This will allow you to “see” only what the eye looking through the microscope ocular
sees. In any case, practice keeping both eyes open while looking through the microscope. Eyestrain can
give you headaches.
6. VISION DIFFERS BETWEEN PEOPLE AND ALSO BETWEEN EYES. IT IS LIKELY THAT
WHILE THE IMAGE YOU ARE VIEWING MAY BE IN FOCUS FOR ONE OF YOUR EYES, IT IS
NOT IN FOCUS FOR THE OTHER. THE LEFT OCULAR ON YOUR MICROSCOPE HAS
ADJUSTABLE FOCUS TO ACCOUNT FOR THIS.
TO ADJUST THE OCULAR FOCUS, START BY LOOKING THROUGH THE NONADJUSTABLE RIGHT OCULAR AND COVERING YOUR LEFT EYE WITH THE INDEX CARD
THAT IS IN THE TOP DRAWER AT YOUR SEAT. DON’T CLOSE THE EYE YOU ARE
COVERING! NOW, CAREFULLY FOCUS ON THE IMAGE USING THE FINE FOCUS
CONTROL ON THE MICROSCOPE. ONCE THE IMAGE IS IN FOCUS, COVER YOUR RIGHT
EYE WITH THE INDEX CARD AND LOOK THROUGH THE LEFT OCULAR WITH YOUR
LEFT EYE. ADJUST THE FOCUS OF THE LEFT OCULAR BY TURNING ITS FOCUSING RING
TO THE LEFT OR THE RIGHT UNTIL THE IMAGE IS IN GOOD FOCUS. ONCE THESE STEPS
ARE COMPLETED YOU WILL HAVE MATCHING FOCUS IN BOTH OCULARS. SINCE
SOMEONE ELSE IN ANOTHER LAB SECTION WILL BE USING YOUR MICROSCOPE IT MAY
BE NECESSARY TO PERFORM THIS ADJUSTMENT EACH TIME YOU USE THE
MICROSCOPE.. AGAIN, THIS WILL HELP ELIMINATE EYESTRAIN.
ONCE THE SPECIMEN IS IN FOCUS, IT IS TIME TO ADJUST THE CONDENSER DIAPHRAGM
APERTURE. THIS IS DONE BY ROTATING THE PLASTIC RING ON THE THE CONDENSER
ASSEMBLY THAT IS UNDERNEATH THE STAGE. YOU WILL NOTICE THAT THERE IS A
WHITE DOT ON THE RING AND BELOW THAT A WHITE LINE THAT AT ONE END HAS A
DIAGRAM OF A CIRCLE WITH A HEXAGON IN IT AND AT THE OTHER END, JUST A
CIRCLE..
7. CONDENSER DIAPHRAGM ADJUSTMENT.
a. WHILE LOOKING THROUGH THE OCULAR OF YOUR MICROSCOPE, ROTATE THE RING
CLOCKWISE (TO THER LEFT) ALL THE WAY TO WHERE IT STOPS ROTATING. AT THIS
POINT THE APERTURE IS AT ITS SMALLEST SIZE AND ALLOWS THE LEAST AMOUNT OF
LIGHT TO PASS THROUGH.
24
b. NEXT, SLOWLY TURN THE RING COUNTER-CLOCKWISE (TO THE RIGHT) UNTIL YOU
REACH THE POINT THAT THE VIEWING FIELD IS AS BRIGHT AS IT WILL GET. THE
APERTURE SHOULD BE ADJUSTED TO THIS POINT AND NOT BEYOND IT. YOU NOW
HAVE ADJUSTED YOUR CONDENSER DIAPHRAGM FOR MAXIMUM RESOLUTION AT A
REASONABLE CONTRAST. IF YOU HAVE COMPLETED THIS ADJUSTMENT CORRECTLY,
THE GRADUATED PLASTIC RING ON THE CONDENSER A SHORT DISTANCE FROOM THE
HEXAGON IN THE CIRCLE..
CONTRAST CAN BE INCREASED BY CLOSING DOWN THE CONDENSER DIAPHRAGM TO
ALLOW LESS LIGHT THROUGH; HOWEVER, THIS ALSO CAUSES A DECREASE IN
RESOLUTION. AN INCREASE IN CONTRAST MAY BE HELPFUL IN VIEWING SOME
SLIDES.
THE APPROPRIATE ADJUSTMENT OF THE CONDENSER APERTURE MAY CHANGE
DEPENDING ON WHICH SLIDE YOU’RE VIEWING AND WHAT OBJECTIVE YOU ARE
USING. SO BE AWARE, THAT IT MAY BE HELPFUL IN SOME CASES TO CHANGE THE
ADJUSTMENT OF THE CONDENSER DIAPHRAGM.
8. AFTER THE SPECIMEN IS IN FOCUS AND THE CONDENSER PROPERLY ADJUSTED, IT IS
TIME TO BRING THE FIELD DIAPHRAGM INTO FOCUS AND CENTER IT.
9. FIRST, MAKE SURE THE TISSUE ON YOUR SLIDE IS IN GOOD FOCUS. THEN CLOSE THE
FIELD DIAPHRAGM TO IT’S SMALLEST OPENING BY ROTATING THE PLASTIC KNURLED
RING ON THE FIELD DIAPHRAGM ASSEMBLY COUNTER-CLOCKWISE UNTIL IT STOPS.
10. NOW, BY TURNING THE CHROME-PLATED ADJUSTMENT SCREWS ON THE LEFT AND
RIGHT SIDES OF THE BASE OF THE CONDENSOR ASSEMBLY, LOOK THROUGH THE
OCULARS AND CENTER THE DIAPHRAGM IN THE VIEWING FIELD. CENTERING IS
CRITICAL IF YOU ARE TO OBTAIN THE BEST IMAGE OF THE MATERIAL YOU ARE
LOOKING AT. AFTER YOU HAVE CENTERED THE SMALLEST OPENING OF THE FIELD
DIAPHRAGM, OPEN THE DIAPHRAGM UNTIL THE OPENING ALMOST FILLS THE FIELD.
NOW YOU CAN RE-CENTER THE DIAPHRAGM OPENING FOR EVEN BETTER
ALIGNMENT.
11. ONCE YOU HAVE CENTERED THE FIELD DIAPHRAGM, OPEN THE DIAPHRAGM UNTIL
THE OPENING JUST FILLS THE FIELD OF VIEW. NO FURTHER!
12. IDEALLY, EACH TIME YOU CHANGE OBJECTIVES YOU SHOULD RE-FOCUS, RE-SIZE
AND RE-CENTER THE FIELD DIAPHRAGM IF YOU WISH TO OBTAIN THE BEST IMAGE
POSSIBLE.
WHAT YOU HAVE JUST DONE IS SET YOUR MICROSCOPE UP FOR “PROPER
KOHLER ILLUMINATION”. THIS WILL GIVE YOU THE BEST RESOLUTION
POSSIBLE WITH YOUR MICROSCOPE.
13. ONCE YOU HAVE THE IMAGE OF THE TISSUE YOU ARE VIEWING IN FOCUS WITH A
GIVEN OBJECTIVE YOU MAY ADVANCE THE OBJECTIVE TURRET TO THE NEXT
25
HIGHER MAGNIFICATION AND RE-FOCUS AND READJUST YOUR MICROSCOPE AS
DESCRIBED ABOVE.
----------------------------------------------------------------------------------------------------------THE FOLLOWING INSTRUCTION MUST ALWAYS BE ADHERED TO!!!
WHENEVER YOU ADVANCE TO THE NEXT HIGHER MAGNIFICATION
OBJECTIVE, YOU MUST RE-FOCUS THE IMAGE BEFORE ADVANCING TO AN EVEN
HIGHER MAGNIFICATION!!!
---------------------------------------------------------------------------------------------------------14. NEVER, I REPEAT NEVER, USE THE COARSE FOCUS WITH THE HIGHER POWER
OBJECTIVES (20X, 40X OR 100X objectives).
BEFORE REMOVING A SLIDE FROM THE STAGE!!!!
WHEN YOU ARE FINISHED VIEWING, MOVE THE OBJECTIVE TURRET TO BRING THE 4X
OR 10X OBJECTIVE INTO POSITION OVER THE VIEWING AREA. THEN REMOVE THE
SLIDE FROM THE STAGE. REMOVING THE SLIDE FROM UNDER HIGHER POWER
OBJECTIVES MAY CAUSE THE SLIDE SURFACE TO DRAG OVER THE OBJECTIVE LENS
SINCE THE LENS IN THESE OBJECTIVES WILL BE VERY CLOSE TO THE SLIDE. THIS
COULD RESULT IN DAMAGE TO THE LENS.
OIL IMMERSION (not used in this course)
OIL IMMERSION VIEWING IS USED TO 1) DIRECT THE GREATEST AMOUNT OF LIGHT
THROUGH THE OBJECTIVE LENS and 2) TO ACHIEVE THE HIGHEST POSSIBLE RESOLUTION
WHEN VIEWING THROUGH THE HIGHEST POWER OBJECTIVES.
FOR YOUR MICROSCOPE, THIS WOULD BE WHEN VIEWING SLIDES WITH THE 100X
OBJECTIVE.
IN THIS COURSE, THE 4X, 10X, AND 40X OBJECTIVES WILL BE SUFFICIENT FOR ALL OF
YOUR LAB WORK. HOWEVER, IN SOME INSTANCES, THE OIL IMMERSION OBJECTIVE
(100X) MAY BE USEFUL. IN ORDER FOR THIS OBJECTIVE TO PROVIDE AN IMAGE THAT IS
IN GOOD FOCUS, A DROP OF OIL MUST BE PLACED BETWEEN THE OBJECTIVE LENS AND
THE SLIDE.
15. BEFORE PERFORMING OIL IMMERSION MICROSCOPY, YOU MUST FIRST GO THROUGH
THE PROCEDURES NECESSARY TO OBTAIN GOOD FOCUS WITH THE 40X OBJECTIVE.
16. THAT ACCOMPLISHED, MOVE THE OBJECTIVE TURRET SUCH THAT THE SPACE
BETWEEN THE 40X AND 100X OBJECTIVES IS OVER THE VIEWING AREA.
17. NOW, PLACE A SMALL DROP OF IMMERSION OIL ON THE SLIDE OVER THE POINT
WHERE THE OBJECTIVE LENS WILL RESIDE WHEN YOU MOVE IT INTO POSITION OVER
THE VIEWING AREA. THIS POINT IS WHERE YOU CAN SEE THE LIGHT BEAM PASSING
THROUGH THE SLIDE. THE DROP OF OIL SHOULD BE VERY SMALL, NOT MUCH IS
NEEDED AND THE LESS THERE IS, THE EASIER IT WILL BE TO CLEAN THINGS UP
WHEN YOU ARE FINISHED.
18. NEXT, ROTATE THE OBJECTIVE TURRET TO BRING THE 100X OBJECTIVE OVER THE
VIEWING AREA. DO THIS CAREFULLY, AND WATCH TO MAKE SURE THAT THE
26
OBJECTIVE LENS DOES NOT CONTACT THE SURFACE OF THE SLIDE. IF YOU FOCUSED
PROPERLY WITH THE 40X OBJECTIVE IN STEP 10, THERE WILL BE NO PROBLEM.
19. ONCE THE 100X OBJECTIVE IS MOVED INTO POSITION, THE LENS WILL BE IMMERSED
IN OIL. NOW, USING ONLY THE FINE FOCUS CONTROL, LOOK THROUGH THE OCULARS
AND FOCUS ON THE SLIDE. THIS SHOULD REQUIRE ONLY A SMALL ADJUSTMENT OF
THE FINE FOCUS KNOB.
WHEN YOU ARE DOING THIS FOCUSING, IT IS IMPORTANT TO BE VERY CAREFUL. IT
WILL NOT TAKE MUCH ROTATION OF THE FINE FOCUS KNOB TO CAUSE THE 100X
OBJECTIVE TO RAM THROUGH THE SLIDE, DAMAGING BOTH THE OBJECTIVE AND
THE SLIDE.
BE CAREFUL!!!
20. ONCE THE TISSUE ON THE SLIDE IS IN FOCUS, IT MAY BE MOVED AROUND ON THE
STAGE. AS LONG AS THE DISTANCE MOVED IS NOT TOO LARGE, THE OIL DROPLET
WILL REMAIN BETWEEN THE 100X OBJECTIVE AND THE SLIDE. YOU WILL NOTICE
THAT WHEN THE SLIDE IS MOVED, IT WILL BE NECESSARY TO RE-FOCUS THE 100X
OBJECTIVE USING THE FINE FOCUS CONTROL. AT VERY HIGH MAGNIFICATIONS,
VERY SMALL CHANGES IN THE DISTANCE BETWEEN THE SLIDE AND THE OBJECTIVE
WILL CAUSE THE IMAGE TO GO OUT OF FOCUS. IRREGULARITIES ON THE SLIDE AND
ON THE STAGE OF THE MICROSCOPE ARE LARGE ENOUGH TO CAUSE SUCH CHANGES
IN FOCUS.
ONCE YOU ARE DONE VIEWING A SLIDE UNDER OIL IMMERSION, IT WILL BE
NECESSARY TO CLEAN BOTH THE SLIDE AND THE OBJECTIVE.
21. TURN THE OBJECTIVE TURRET SUCH THAT THE SPACE BETWEEN THE 100X AND
LOWEST POWER OBJECTIVE IS OVER THE VIEWING AREA.
22. REMOVE THE SLIDE FROM THE STAGE AND THOROUGHLY WIPE THE OIL FROM ITS
SURFACE USING A PIECE OF LENS PAPER. MORE THAN ONE PIECE OF LENS PAPER
MAY BE REQUIRED. WHILE SOME PRESSURE MUST BE USED IN ORDER TO CLEAN THE
OIL FROM THE SLIDES SURFACE, BE CAREFUL NOT TO PRESS TOO HARD. IT IS
POSSIBLE TO CAUSE THE COVERSLIP TO SLIDE OFF THE SLIDE IF TOO MUCH
PRESSURE IS USED.
DO A GOOD JOB OF CLEANING THE SLIDE SO THAT YOU WILL NOT HAVE TO CLEAN IT
BEFORE VIEWING IT IN THE FUTURE. DRIED OIL IS HARD TO REMOVE!
23. REPLACE THE SLIDE IN YOUR SLIDE BOX.
24. NEXT, THOROUGHLY WIPE THE 100X OBJECTIVE WITH A NEW, CLEAN PIECE OF LENS
PAPER. AGAIN, IT MAY BE NECESSARY TO DO THIS MORE THAN ONCE, WITH MORE
THAN ONE PIECE OF LENS PAPER.
25. WIPE UP ANY EXCESS OIL THAT IS ON THE MICROSCOPE STAGE.
26 PUTTING MICROSCOPE AWAY:
27
1.
2.
3.
4.
5.
6.
7.
8.
Make sure 4X objective is over viewing area
Raise stage to highest point
Raise condensor if necessary
Fold electrical cord between stage and condensor
Remove plastic cover from cabinet.
Put scope in cabinet with oculars facing back of cabinet.
Put Plastic cover back on scope.
Close cabinet door
CONGRATULATIONS!
YOU HAVE JUST FINISHED A SHORT COURSE IN MICROSCOPY. THE INSTRUCTIONS
ABOVE ARE TAILORED TO THE MICROSCOPES USED IN THIS COURSE. THEY MAY NOT BE
COMPLETELY ADEQUATE FOR MORE SOPHISTICATED MICROSCOPES. IF YOU HAVE THE
OPPORTUNITY TO USE A MORE SOPHISTICATED MICROSCOPE IN THE FUTURE, BE SURE
TO REVIEW THE INSTRUCTION MANUAL THAT COMES WITH THE MICROSCOPE BEFORE
USING IT. FOLLOWING THIS COURSE OF ACTION WILL SAVE YOU TIME, THE HIGH COST
OF REPAIRS, AND PROVIDE THE BEST VIEWING.
A FINAL REVIEW OF AN IMPORTANT POINT.
WHENEVER YOU CHANGE SLIDES, OR LOSE FOCUS ON SLIDES YOU ARE VIEWING,
ALWAYS START YOUR VIEWING WITH THE 4X OR 10X OBJECTIVES. FOCUS ON
SPECIMEN, AND THEN SWITCH TO HIGHER POWER OBJECTIVES.
NOT FOLLOWING THIS PROCEDURE WILL LEAD TO BROKEN SLIDES AND DAMAGED
OBJECTIVES. BOTH ARE EXPENSIVE. PARTICULARLY THE OBJECTIVES WHICH, FOR YOUR
MICROSCOPES, CAN COST AS MUCH AS $400.00 EACH. ON MORE SOPHISTICATED
MICROSCOPES, THE COST OF OBJECTIVES CAN BE $2000.00 - $10,000.00 EACH DEPENDING
ON THE TYPE OF OBJECTIVE..
IF YOU DAMAGE ANY OF YOUR OBJECTIVES, IT MAY BE WEEKS BEFORE WE CAN GET A
REPLACEMENT. YOU MAY BE WITHOUT THE BENEFIT OF THAT OBJECTIVE ON YOUR
MICROSCOPE FOR AS LONG AS IT TAKES.
28
Lab Handout 2A VERTEBRATE DEVELOPMENT BIOL 4410
ROUTINE METHODS
Units of measurement.
METRIC SYSTEM ONLY!
Common units of measurement encountered when working with histological sections are,
Meter (m) = 100 cm = 1000 mm = 106 µm = 109 nm = 1010 Å
Centimeter (cm) = 0.01 m = 100 mm = 10,000 µm = 10,000,000 nm - 100,000,000 Å
Millimeter (mm) = 0.001 m = 0.1 cm = 1000 µm = 1,000,000 nm = 10,000,000 Å
Micron = micrometer (µ or µm) = 0.000001 m = 0.0001 cm = 0.001 mm = 10-6 m = 1000 nm = 10,000 Å
Nanometer (nm) = millimicron (mµ ) = 0.000000001 m = 0.001 µm = 10-9 m = 10 Å
Angstrom = Å = 0.1 nm = 0.0000000001 m = 10-10 m
HISTOLOGICAL METHODS:
While the science of Histology involves use of both the light and electron microscopes, the term
histological generally refers to the examination of tissues with the light microscope. i.e. If you talk about a
histological study, you are generally referring to an investigation using the light microscope. An
investigation using the electron microscope is generally referred to as an ultrastructural study.
BE AWARE, HOWEVER, THAT THIS IS NOT AN ABSOLUTE RULE. SOME INVESTIGATORS
WILL USE THE TERM HISTOLOGICAL TO REFER TO INVESTIGATIONS USING THE
ELECTRON MICROSCOPE.
In examining histological sections with the light microscope in this class we will be dealing with
measurements on the order of the um. For instance, cells are generally on the order of 10 - 20 µm in
diameter; however, some types are smaller, say 1 - 9 µm. IN FACT, THE SMALLEST STRUCTURES
YOU CAN SEE (RESOLVE) WITH THE LIGHT MICROSCOPE ARE ABOUT 0.2 µm DIAMETER,
LENGTH OR WIDTH.
EXAMPLES:
SOME CELLS ARE QUITE SMALL.
Red blood cells,
erythrocytes - 8 µm
29
Unicellular phytoplankton
Gymnodinium microadriaticum - 8 µm
Pavlova lutheri - ~7 µm
Some bacteria - 1 µm
OTHER CELLS ARE MUCH LARGER:
Chicken egg - 7 cm
slug neuron - 500 µm
human egg - 140 µm
In working with histological sections for the light microscope, we are working with 3 dimensions;
however, one of those dimensions, namely the thickness of the section, is generally quite small. The
sections on your slides will be on the order of 1 - 20 µm in thickness depending on the technique used to
prepare them and/or what sort of tissue the sections were taken from.
WHY SO THIN?
You may ask why sections are so thin, or why the thickness varies. I think the why part of the question is
fairly self-evident. In most cases, light must pass through the section in order for us to observe the
structure of the tissue the section is composed of. If the section is too thick it may be naturally opaque, or
it may stain too heavily to allow sufficient light to pass through it.
The thicker the section, the less detail can be see since structures are superimposed over or under each
other
There are exceptions to this general rule of thinness. In some investigations reflected light is used for
observation of tissues. For instance, whole organisms (say an insect) or very thick sections might be
viewed in this manner. In other cases, some types of fine detail cannot be adequately observed if a section
is too thin.
A few pages hence, we will be talking about fixation, embedding and sectioning techniques. All of these
can have an effect on how thin a section can be. Some types of fixation, embedding, or sectioning will not
allow for very thick sections. Other types will not allow for very thin sections.
ULTRASTRUCTURAL METHODS
The term ultrastructural is used to refer to investigations of tissue structure that utilize the electron
microscope. In ultrastructural investigations we are usually talking about measurements ranging from a
few um down to fractions of a nanometer. IN FACT, THE SMALLEST OBJECTS THAT CAN BE
SEEN WITH AN AVERAGE ELECTRON MICROSCOPE ARE ON THE ORDER OF 5-20 A IN
DIAMETER OR LENGTH. Even finer resolution than this can be achieved.
30
Ultrastructural investigations often utilize very thin sections of tissue (60 - 130 nm usually) - Such
microscopy is called transmission electron microscopy, the electron beam passes through section and
forms an image on a fluorescent screen.
In another type of electron microscopy, thick sections or pieces of whole organisms can be examined with
the electron microscope using a technique that is analogous (but definitely not homologous) to the
reflected light technique described above. This type of electron microscopy is called scanning electron
microscopy. The same principles concerned with why sections vary in thickness and why they must be
thin that we discussed relative to light microscopy are also applicable in electron microscopy. Of course,
in the case of electron microscopy we are talking about an electron beam rather than a light beam, but the
properties are similar so we can treat light and electron beams in much the same way.
BACK TO SECTION THICKNESS!
Sections for both light and electron microscopy are, of course, 3-dimensional. They have length, width,
and thickness. However, since they are very thin for most intents and purposes we often treat sections as
2-dimensional objects. THIS CAN BE DANGEROUS RELATIVE TO YOUR UNDERSTANDING OF
WHAT YOU ARE LOOKING AT!
It’s important not to loose track of the fact that tissue sections are components of a 3-dimensional object.
In order for you to gain a better understanding of how a sectioned organ or tissue is constructed, it is
important to consider how a 3 dimensional object might look in sections taken at different angles (i.e.
with the object in different orientations with respect to the knife blade that cuts the sections). Your
understanding of the structure of cells, tissues, organs, and embryos will be totally dependent on whether
or not you are able to relate the essentially 2-dimensional sections on a slide to the 3-dimensional object
that they are parts of.
ONWARD TO PREPARATION OF TISSUES FOR MICROSCOPIC EXAMINATION.
In order to study tissue and cellular structure, tissues must be prepared for microscopic examination.
Two major categories
1. Methods involving direct observation of living cells
2. Methods involving observation of dead cells in which the cellular structure has been preserved in some
manner.
For the purposes of this course, you will be mainly concerned with the second of these two categories.
You will be looking at permanent preparations of embryos, organs, tissues and cells that have undergone
processes called
1. Fixation, 2. embedding, 3. sectioning, and 4. staining.
To understand why this is the case, it might be best to first consider the characteristics of living tissues
when prepared for microscopic examination.
While a number of kinds of information can be gleaned from the examination of living tissues, there are
certain drawbacks that limit the amount and kind of information that may be obtained.
31
1. May be too thick.
2. opaque or translucent
3. live cells die and fall apart if sectioned, so there will often be dead tissue over and/or under the live
tissue. This dead tissue can interfere with observations.
4. Low contrast
5. Methods to increase contrast limited to vital stains or special types of microscopy (phase, interference,
or dark field microscopy).
6. Cannot be examined while alive with electron microscope. i.e. in living tissues you cannot examine
ultrastructure, sub-cellular structure with the electron microscope.
It is important to realize that even with these inherent problems, examination of living cells or tissues can
provide very important information for our understanding of structure and function.
However, detailed structure (that is cellular, sub-cellular, and often chemical structure) of cells and tissues
is best observed in preserved, dead material.
So, you might say, all right, that’s easy, we’ll just kill the tissue, section it, and look at it. IT’S NOT
THAT SIMPLE. THERE ARE A NUMBER OF IMPORTANT CONSIDERATIONS.
FIRST, TISSUES MUST BE FIXED:
FIXATION
1. You not only want to kill the tissue, you also want to preserve its structure. It is imperative that the
original structure of the live tissue be preserved as closely as possible to it’s original condition. Thus,
you want a fixative that will not disrupt the structure of the tissue.
Qualities of a good fixative.
a. Fast penetration - fast fixation, so enzymes, membranes, etc. are fixed before they can either degrade or
cause degradation of cellular structure.
b. Similar temperature, pH, and osmolarity to cytoplasm of cells composing tissue - minimizes shrinkage
and/or swelling of cellular components.
c. Fixative should cause sufficient cross-linking of proteins, such that the tissue will maintain its integrity
during embedding and sectioning.
d. Minimal change in structure of molecules composing cells and extracellular matrix. This is particularly
important in preparations that are to be used in histochemical or immunocytochemical studies.
Obviously, things have to be balanced out. You can’t optimize all these qualities of good fixation at once.
So qualities of a fixative will be determined by what kind of tissue you’re fixing and what you want to do
with it after it’s fixed.
32
The most common fixatives for light microscopy are
1. Formalin
2. Alcohols
3. Mercuric dichloride
4. Potassium dichromate
5. and various acids, e.g. picric acid
Often mixtures of 2 or more different fixatives, along with other reagents (such as buffers), are used for
fixation of tissues.
The most common fixatives for electron microscopy are
1. Glutaraldehyde
2. Osmium tetroxide
In electron microscopy, pH and osmolarity are very important since ultrastructural examinations involve
looking at the sub-structure of organelles such as mitochondria or at molecules. These are structures that
are easily disrupted by inappropriate pH and osmolarity of the fixative.
EMBEDDING
Tissues are sometimes frozen to make them rigid enough for sectioning, but usually they are embedded in
a supporting material. This material is in liquid form initially so that it can infiltrate the cells of the tissue.
It is then hardened in some manner to form a rigid block that can be sectioned.
How embedding is accomplished depends on the medium that the tissue is embedded in.
Light microscopy
The classical medium for embedding tissues for light microscopy is wax. Wax is still used for the majority
of histological procedures even today.
Wax is not water miscible, so, since fixatives usually contain water, tissues must undergo dehydration
after fixation.
This is usually done by transferring the fixed tissue through an alcohol series, though acetone is
sometimes used.
To dehydrate a fixed tissue it might be passed through a series of solutions in the following order.
After fixation,
Rinse in distilled water, 30% ethanol, 50%, 70%, 80%, 95%, 100%, 100%, 100%, toluene or xylene,
toluene or xylene, hot (60o C) wax. Finally, the wax is cooled to form a hard block that can be sectioned.
Timing of treatment and temperature are very important. These must be adjusted to preserve tissue
structure as closely as possible to the original living tissue.
33
Electron microscopy
Similar procedures are used for embedding tissue in plastic polymers such as Polybed 812, Epon, or
Araldite. One difference is that propylene oxide is used after 100% alcohol rather than toluene or xylene.
This allows for better preservation of the tissues ultrastructure.
General procedures are essentially the same as in wax embedding except that tissues are dehydrated
through propylene oxide and then transferred to mixtures of propylene oxide and a plastic such as Epon,
and finally to 100% plastic. A catalyst mixed with the plastic is responsible for its polymerization
(hardening). Polymerization is usually accomplished at temperatures of about 60 o C, though with some
plastic formulations ultraviolet light can be used to polymerize the plastic at low temperatures (e.g. - 20 o
C).
Tissues embedded in plastic are generally much better preserved than those embedded in wax; however,
plastics are more difficult to section and sections embedded in plastics such as Epon require special
treatment if they are to be used in the majority of histochemical techniques. Often they can’t be used
because the molecular structure of the embedded tissues has been changed by the polymerization process
to the point that the stains used in histochemical procedures for the light microscope will no longer
recognize the substance that they are supposed to stain.
In recent years, water miscible plastics such as Polyscience’s JB-4 medium have come into use. These
circumvent the need for extensive dehydration procedures and are readily usable with most stains without
special treatment of sections prior to staining. These plastics still present some problems with regard to
the ease of sectioning. Hopefully these problems will be overcome in the near future.
Once the tissues are embedded, and the wax or plastic hardened, they are sectioned on a microtome. This
is an instrument designed to cut thin sections from the face of a block of wax or plastic that contains the
embedded tissue.
The block moves up and down on the arm of the microtome. A mechanical mechanism retracts the block
away from a knife on the upstroke. The block is advanced one increment of distance on the downstroke
and a section is cut on the knife. The end result is that you get a “ribbon” of sections. In the case of wax,
sections are cut with a steel knife blade. Plastic sections are cut with a glass or diamond knife (to cut
plastic the knife edge must be exceedingly sharp and very hard. Steel is very, very quickly dulled by
plastic).
For light microscopy the sections are picked-up and transferred to a slide for mounting. They are usually
floated on water and then the water is evaporated. Sections adhere to the slide, the wax is removed with a
solvent such as xylene or toluene, the sections are rehydrated, stained, dehydrated, and a coverslip is
mounted over the sections using a non-polar mounting medium such as cedarwood oil, or Permount.
For electron microscopy, sections are cut with a glass or diamond knife, floated onto water as they are cut,
then picked-up with a small, thin copper screen called a grid. The sections are allowed to dry and then are
stained with heavy metals such as uranium and lead.
The final step in both light and electron microscopy is to examine the sections with the microscope.
34
Lab Handout 2B VERTEBRATE DEVELOPMENT BIOL 4410
MITOSIS, MEIOSIS, AND GAMETOGENESIS
HOW MEIOSIS AND MITOSIS DIFFER
MITOSIS
MEIOSIS
1.
Occurs in somatic cells and
the stem cells of the germ
cell line.
1.
Occurs only in gametocyte
stages of the germ cells.
2.
One division resulting in
2 new cells
2.
Two divisions
resulting in 4 new cells.
3.
Each of the 2 new cells
receives one complete pair
of each homologous pair of
chromosomes.
3.
Each of the 4 new
cells receives only one
chromosome of each
homologous pair of
chromosomes.
4.
Each of the 2 new cells
contains a diploid number
(2n) of chromosomes and
diploid (2n) genetic
content.
4.
Each of the 4 new
cells contains a
haploid number (1n) of
chromosomes and
haploid (1n) genetic
content.
35
Lab Handout 2B VERTEBRATE DEVELOPMENT BIOL 4410
MITOSIS AND MEIOSIS IN A DIAGRAMATIC SENSE
Look at “PLOIDY, WHAT IS IT?” on the class web page.
36
Lab Handout 2C VERTEBRATE DEVELOPMENT BIOL 4410
BASIC MICROSCOPY METHODS
In examining slides of sectioned tissues with the light and electron microscopes, one should be aware that
some of the structures observed may not be real, that is, they may be artifacts. Artifacts are the result of
changes in tissues structure or the addition of new structures that are usually the result of fixation,
dehydration, embedding, sectioning, staining, and/or section mounting techniques. Types of artifacts that
are commonly encountered are listed below. Light microscope examples of these are available for
viewing in the auto-tutorial slides available in the lab.
REVIEW OF BASIC ARTIFACTS.
1. Swelling of tissue components
2. Shrinkage of tissue components
Artifact types 1 and 2 are the result of poor fixation and/or dehydration techniques, i.e. osmolarity of
fixative may be wrong, pH wrong, too short a fixation time, dehydration of tissue too rapid. Swelling and
shrinkage can sometimes result in rupture of membranes. This sort of damage is particularly evident at
the ultrastructural level.
3. wrinkles in section
4. tears in section
5. air bubbles
6. dust
Artifact types 3, 4, and 5 are usually the result of poor sectioning technique or poor technique during
mounting of sections. In some cases, poor fixation and/or embedding can be responsible for tears or
wrinkles in sections by modifying fixed tissue consistency such that the tissue cannot be sectioned
without its tearing or wrinkling.
7. stain precipitate
This sort of artifact can result from use of old stain solutions, use of unfiltered stain solutions, mistakes
made during preparation of the stain, or poor staining technique.
THE LIGHT MICROSCOPE:
We have gone over the use of your light microscopes during lab and you have a handout describing how
to set-up your microscope for viewing such that “proper Kohler illumination” is established. In setting up
“proper Kohler illumination” you are adjusting the path of the light such that a minimum of light
reflection within occurs within the scope and the maximum amount of light passes through the center of
the various lenses within the microscope. In addition, light is restricted to the central portion of the lenses.
The reason for this is that their are more and more defects in the image the lens produces as you move
away from its center.
The end result of your adjustments for “proper Kohler illumination” is that you achieve the maximum
resolution of the image of the tissue you are viewing that is possible with your microscopes. This means
that you will be able to see the maximum amount of structure within the tissue that can be seen with your
microscopes.
37
The objective and ocular lenses are responsible for magnifying the image of the specimen being viewed.
Total magnification = Objective magnification X ocular magnification
So for 10X objective and 10X ocular,
Total magnification = 10 X 10 = 100X (this means that the image being viewed will appear to be 100
times its actual size).
For a 40X objective and 10X ocular,
Total magnification = 10 X 40 = 400X
Magnification is not of much value unless resolving power is high.
Resolution is a measure of the ability to distinguish 2 points as two points. That is, when viewing
something through a microscope, how close together can two points
be that you can still see some space between them?
**
**
We can’t say much more about resolution without a few words about numerical aperture (n.a. or NA). The
value for numerical aperture measures to what extent the light that passes through a specimen is spread out
over and collected by the objective lens. The light that passes through the specimen contains information
about what the specimen looks like, that is, about its structure.
AS YOU READ THE FOLLOWING DISCUSSION ON NUMERICAL APERTURE AND
RESOLUTION, IT MAY HELP TO REFER TO FIGURE 1-3 IN THE HISTOLOGY TEXT (PAGE 5)
ON THE SHELF AT THE BACK OF THE LAB.
If we consider the cone of light that originates from the specimen and enters the objective lens, Numerical
aperture can be defined as,
NA = n x sin µ
( x is the multiplication symbol)
n = refractive index of substance between specimen and objective lens (usually air, n = 1.0; quartz, n =
1.5; glass, n= about 1.5; water, n = 1.3)
µ = 1/2 the aperture angle (also called the semiangle). The aperture angle is the angle described by the
cone of light that enters the objective lens after passing through the specimen. This angle will depend on
the curvature of the lens and also on how close the objective lens is to the specimen when it is in focus.
So, for an objective with an aperture angle of 120 o with air between specimen and objective lens,
NA = 1 x sin 60o = sin 60 o = 0.87
If oil with refractive index of 1.5 is used between objective lens
and specimen,
NA = 1.5 x sin 60 o = 1.5 x (.87) = 1.31
38
Now, numerical aperture is important because it allows us to calculate the resolving power of the
objective. Remember, that’s what we really were interested in determining initially.
R = 0.61 x ( λ / NA)
R = resolution of the objective
λ = wavelength of light (average value for white light ~ 550 nm).
NA = numerical aperture
So, for the air situation,
R = 0.61 x (550nm/.87) = 386 nm = 0.000000386 m = 0.386 µm
For oil immersion,
R = 0.61 x (550nm/1.31) = 256 nm = 0.000000256 m = 0.26 µm
Thus, one can see that higher resolution is possible if the substance lying between the specimen and the
objective lens has a refractive index as close as possible to that of the lens itself without exceeding the
lens’ refractive index.
It is important to realize that while both the ocular and objective lenses are responsible for the final
magnification on a compound microscope, ONLY the objective lens is responsible for resolution.
The discussion above should demonstrate the importance of resolution. By using the appropriate lenses I
can create extremely high magnifications, say 5000X with the light microscope. However, magnification
tells us nothing about resolution. If resolution of objective lens is 0.3 µm, no matter how much I magnify
the specimen image, the resolution will remain the same. At 5000X, I will still only be able to resolve
points a minimum of 0.3 µm apart. Points that are closer together may be visible, but the will be
superimposed and blurred, appearing as one fuzzy point. So nothing has been gained by increased
magnification. The amount of visible information available at 5000X is the same as at lower
magnifications of 1500X.
Using the mathematical equations given above and the values for maximum numerical aperture attainable
with the lenses of a light microscope it can be shown that the maximum useful magnification on a light
microscope is between 1000X and 1500X. Higher magnification is possible, but resolution will not
improve.
In addition to numerical aperture and an incorrect light path, there are 3 major lens defects that can affect
the quality of the image in a compound microscope and result in decreased resolution.
These are,
A. Chromatic aberration - caused by spherical a lens bringing different wavelengths of light into focus at
different levels. Thus, you get multiple images superimposed on top of each other. This defect is
corrected in achromatic objectives.
39
B. Spherical aberration - optical quality of image lessened due to the fact that the center of lens has
slightly different qualities than the edges. Both spherical and chromatic aberration are corrected in
apochromatic objectives.
C. Curvature of field - causes image to be in focus centrally, but out of focus peripherally or vice versa.
This defect is corrected in planar objectives.
The type of objective, magnification, numerical aperture, and even the best coverslip thickness to use on
your slides is listed on the side of an objective.
There are a number of special types of light microscopy that can enhance certain features of a specimen
that is being examined. Some of these are listed below.
1. Phase contrast microscopy - takes advantage of phase differences in light beam that are caused by
different refractive indexes of components within a tissue.
Consider air, n=1.0; water, n=1.3; glass, n=1.5. Light travels fastest through air and slowest through
glass. Thus, if a light beam encounters three different spaces of equal thickness that are filled with air
water, and glass, the beam will emerge first from the air filled space and last from the glass filled
space. These light beams are said to be out of phase with each other.
In the phase contrast microscope, the condenser and objectives are specially made to detect the phase
differences of light passing through different components within a tissue specimen. The construction of
the condenser and objective lenses is such that these phase differences are made visible by increasing
the contrast between light waves of different phase. As a result, components of cells that are normally
of low contrast (clear or nearly clear), are given higher contrast and, thus, made visible.
2. Polarizing microscopy - A polarizing filter (called the polarizer) is placed below the condenser and
allows only light vibrating in one plane to reach the condenser. A second polarizing filter (called the
analyser) is placed between the objective and ocular. If these two filters are oriented such that their axes
of light transmission are perpendicular, no light will pass through the analyser to the ocular. So nothing
will be seen. One use of polarizing light microscopy is related to the fact that certain crystals found in
or associated with some cells can bend light waves because of their refractive index. If some of the
light waves that have passed through the polarizer are bent into different planes as they pass through
crystalline parts of the specimen, then some of these light waves will be able to pass through the
analyser even if it is oriented at 90o to the polarizer. This property of crystals to bend polarized light
waves is called birefringency. It is important in identifying certain crystalline structures in or associated
with cells.
3. Interference or Nemarski interference microscopy. - this is another method utilized to observe structures
of different refractive index, but similar optical density. It is not the same as phase contrast microscopy.
Nemarski interference microscopy requires 2 different light beams that are recombined after passing
through the specimen. Differences in phase between the two beams are visualized as depth. The result
is an image with depth (sort of 3-D). This type of microscopy is particularly useful for viewing living
cells.
ELECTRON MICROSCOPY
Functioning of this instrument is dependent on the fact that an electron beam has many properties that are
similar to a light beam.
40
In fact, a beam of electrons may be treated as either 1.) a beam of particles or 2.) as a wave (i.e. like a light
wave). As it turns out, both properties are necessary in order for an electron microscope to work. The fact
that the effective wavelength of an electron beam is very much smaller than that of the shortest visible
light wave makes very high resolution possible with this instrument (i.e. 5 - 20 A)
Recall that,
R = 0.61 x (λ/NA)
This means that very high useful magnification is possible since very small distances between two points
can be resolved. The highest magnification commonly used with the electron microscope is 200,000X.
However, higher useful magnifications are possible.
Suffice it to say, that for the purposes of this course, we can consider the electron microscope in relatively
simple terms. An electron beam is produced by inducing a high voltage between a cathode (-) and an
anode (+). Electromagnets are used to direct the path of this beam and also to act as magnetic lenses that
are responsible for magnification of the image of the specimen. As the electron beam passes through the
specimen, electrons are either unaffected, scattered, or absorbed by the tissues of the specimen and various
stains (usually heavy metals) that have been applied to the tissues. The unaffected electrons and many of
the scattered electrons pass through the specimen and then are focused by magnetic lenses on a fluorescent
viewing screen. The number of electrons hitting various parts of this screen determine how brightly these
parts fluoresce and thus form an image of the specimen on the screen that can be examined by the person
using the scope. In addition, the focused electrons can be used to expose photographic film from which
black and white pictures can be printed. The photographs produced are actually more useful in interpreting
electron microscope images because they are permanent and of higher contrast than the fluorescent image.
41
Laboratory Identification (ID) Lists
Overview
In the vertebrate embryology laboratory we study reproductive and embryonic structures at different
stages of development. Some of the terms we use are stage-specific (e.g., lens vesicle), whereas others
remain consistent throughout development (e.g., head).
The Lab ID Lists contain the terms for structures and processes for which you are responsible. Obviously,
you can’t point at a process, but you can point to the structure that performs that process. So yes, you need
to relate form and function.
Just as an embryo begins development from apparent simplicity and progresses toward greater
complexity, so does the list of terms you will learn in this course. If you have already peeked at the list for
later stage embryos, we say, “Courage, Grasshopper! It can be done.” Don’t try to just memorize terms.
Attach them to your visual images of structures. That means that you actually have to find them and look
at (study, ponder, evaluate) them.
Repetition is the “engine” of memory, and as you progress through the course you will find that many
terms will be repeated in subsequent lists. You will also find that some structures have more than one
name. With each succeeding stage of development, you are responsible for those terms previously studied,
in addition to those being introduced anew. For the embryos of various developmental stages (e.g., frog,
chick, pig) the first time a term is added to the list, it is italicized, but not subsequently. As you progress to
later stages, you will be able to identify the new terms easily by this style.
In the amniote (e.g., chick, pig) lists, the terms are grouped according to origin (e.g., extraembryonic or
embryonic), or function (e.g., nervous system, digestive system, etc.). Some terms apply to tissues that
involve both embryonic and extraembryonic structures (e.g., somatic and splanchnic). Observe that when
a column head is followed by an ellipsis (e.g., Embryonic…) and a term in that column is preceded by an
ellipsis (e.g., …mesoderm), you are responsible for identifying (e.g.,) “embryonic mesoderm.”
As you identify a structure on your slides, place a check mark in the space beside its name to keep track of
your progress. Most of the amniote structures to identify are embryonic in nature, so the middle column is
usually the longest, giving you room to make notes on either side of the entries. (Just one more service we
provide.)
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to
which you cannot point, but sometimes they are very small or obscure structures. Each slide set is
unique, and not all embryos identically labeled are at exactly the same developmental stage. It is
possible that a particular structure is too rudimentary to be identified on your slides, but you must
still know the pertinent information about that structure. Check with your instructor to be certain
that you haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets
of a particular stage of development.
42
Laboratory Identification List
Testis & Spermatogenesis
NOTE: Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you
cannot point, but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so
labeled are at exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be
identified on your slides, but you must still know the pertinent information about that structure. Check with your TA to be
certain that you haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a
particular stage of development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Grasshopper Testis
Vertebrate Testis
(frog, rat, rabbit, monkey, human)
____ apical end of lobe
____ cyst
____ septum
____ interstitial cells of Leydig
____ seminiferous tubule
____ septum
____ Sertoli cell
Spermatogenesis
____ *mitosis
____ *meiosis (I & II)
____ spermatogonium
Spermatogenesis
____ *mitosis
____ *meiosis (I & II)
____ spermatogonium
Meiosis I
____ primary spermatocyte
Meiosis I
____ primary spermatocyte
Stages of First Meiotic Prophase
____ leptotene
____ *zygotene
____ pachytene
____ diplotene
____ diakinesis
____ tetrad
Stages of First Meiotic Prophase
____ leptotene
____ *zygotene
____ pachytene
____ diplotene
____ diakinesis
____ tetrad
____ reductional division
____ *reductional division
Meiosis II
____ secondary spermatocyte
____ *dyad
____ *equational division
____ *spermiogenesis (=spermateleosis,
=spermatozoan metamorphosis)
____ spermatid
____ spermatozoon (=spermatozoan)
____ sperm head
____ acrosome
____ nucleus
____ midpiece
____ tail (=flagellum)
____ *spermiation
Meiosis II
____ secondary spermatocyte
____ *dyad
____ *equational division
____ *spermiogenesis (=spermateleosis,
=spermatozoan metamorphosis)
____ spermatid
____ spermatozoon (=spermatozoan)
____ sperm head
____ acrosome
____nucleus
____ midpiece
____ tail (=flagellum)
____ *spermiation
43
Laboratory Identification List
Ovary & Oogenesis
NOTE: Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you
cannot point, but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so
labeled are at exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be
identified on your slides, but you must still know the pertinent information about that structure. Check with your TA to be
certain that you haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a
particular stage of development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Amphibian (frog)
____ animal pole
____ vegetal pole
____ *oogonium
Avian (chick)
____ cortex
____ medulla
____ *oogonium
Mammalian (cat)
____ germinal epithelium
____ tunica albuginea
____ cortex
____ medulla
____ corpus luteum
____egg nests
____ *oogonium
____ ovarian follicle
____ follicle cells
____ theca folliculi
____ theca externa
____ theca interna
____ *vitelline membrane
____ ovarian follicle
____ follicle cells
____ theca folliculi
____ stratum granulosum
____ ovarian follicle
____ follicle cells
____ primordial follicle
____ primary follicle
____ secondary follicle
____ tertiary follicle
(=Graafian follicle)
____ theca folliculi
____ theca externa
____ theca interna
____ stratum granulosum
____ antrum
____ liquor folliculi
____ cumulus oophorus
____ *corona radiata
____ zona pellucida
____ oocyte (primary,
*secondary)
____ germinal vesicle
____ lampbrush chromosome
____ nucleolus
____ nucleus
____ yolk
____ oocyte (primary,
*secondary)
____ germinal vesicle
____ nucleus
____ yolk
____ oocyte (primary,
*secondary)
____ nucleus
____ germinal vesicle
44
Laboratory Identification List
Starfish Development
For identifications that involve specific embryonic structures and/or tissues, it will be important to
start determining which germ layer (ectoderm, mesoderm, endoderm) from which the tissue or
structure is derived. Be sure you can identify the various embryonic/larval stages. You will not
always be able to find the landmarks/structures necessary to identify the animal and vegetal poles;
however, you should know what these landmarks/structures are and be able to use them to make these
identifications.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Oocyte—Zygote
Early Cleavage
Blastula
____ fertilization
membrane
____ perivitelline
space
____ germinal
vesicle
____nucleus
____*animal pole
____*vegetal pole
____ fertilization
membrane
____ perivitelline
space
____ blastocoel
____ blastomere
____ fertilization
membrane
____ perivitelline
space
____ blastocoel
____ blastomere
Gastrula
____ archenteron
____ archenteric
vesicle
____ blastopore
(=anus)
____ blastocoel
____ coelomic
____*animal pole ____*animal pole
sacs (late
____*vegetal pole ____*vegetal pole
gastrula)
____ gastrocoel
(archenteric
cavity)
____*mesenchyme
cells
____ oral lobe
(late
gastrula)
____ stomodeum
=
mouth (mid
to late
gastrula)
____ animal pole
____ vegetal pole
45
Bipinnaria
____ blastocoel
____ stomodeum
= mouth
____ oral field
____ esophagus
____ stomach
____ intestine
____ anus
____ coelomic
sac
____ ciliated
band
Laboratory Identification List
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you cannot point,
but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so labeled are at
exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be identified on your
slides, but you must still know the pertinent information about that structure. Check with your TA to be certain that you
haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a particular stage of
development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Early Frog Development (page 1 of 2)
Early Frog: Cleavage through Gastrulation
Early-Mid Cleavage
____ pigmented cortex
____ animal
hemisphere
____ animal pole
____ vegetal pole
____ fertilization
membrane
____ blastomere
____ macromere
____ micromere
____ cleavage furrow
____ *gray crescent
____ nucleus
Blastula
____ pigmented cortex
____ animal
hemisphere
____ animal pole
____ vegetal pole
____ fertilization
membrane
____ blastomere
____ macromere
____ micromere
Early Gastrula
____ pigmented cortex
____ animal
hemisphere
____ animal pole
____ vegetal pole
____ fertilization
membrane
____ nucleus
____ blastocoel
____ blastoderm
____ *blastulation
____ blastocoel
____ blastopore
Yolk Plug
____ pigmented cortex
____ fertilization
membrane
____ macromere
____ micromere
____ dorsal lip of
blastopore
____ blastocoel
____ blastopore
____ dorsal lip of
blastopore
____ * ventral lip of
blastopore
____ archenteron
(=gastrocoel)
____ yolk plug
____ *emboly
____ *epiboly
____ *involution
____ *fate map
Presumptive…
____ …neural
ectoderm
____ …non-neural
ectoderm
____ …mesoderm
____…chordamesoderm
____ …endoderm
46
Early Frog Development (page 2 of 2)
Early Frog: Neurula Stage
Neural Plate – Neural Fold Stage
Neural Tube Stage
Nervous System
____ neural plate
____ neural fold
____ neural groove
____ *neural crest
____ neurocoel
Nervous System
____ *neural crest
____ neurocoel
____ neural tube
____ *prosencephalon
____ *optic vesicle
____ *mesencephalon
____ *rhombencephalon
____ spinal cord
Digestive System
____ *foregut
____ *liver diverticulum
____ midgut
Digestive System
____ pharynx
____ liver diverticulum
____ midgut
____ *hindgut
Miscellaneous Organs & Tissues
____ ectoderm (neural, non-neural)
____ epidermis
Miscellaneous Organs & Tissues
____ ectoderm (neural, non-neural)
____ epidermis
____ *adhesive gland
____ *head mesenchyme
____ mesoderm
____ notochord
____ somite mesoderm (=epimere)
____ intermediate mesoderm
(=mesomere)
____ lateral plate mesoderm
(=hypomere)
____ hypochordal (subnotochordal) rod
____ endoderm
____ yolk endoderm
____ *head mesenchyme
____ mesoderm
____ notochord
____ somite mesoderm (=epimere)
____ intermediate mesoderm
(=mesomere)
____ lateral plate mesoderm (=hypomere)
____ hypochordal (subnotochordal) rod
____ endoderm
____ yolk endoderm
47
Laboratory Identification List
4 – 7 mm Frog Embryo
Page 48 of 3
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you cannot point,
but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so labeled are at
exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be identified on your
slides, but you must still know the pertinent information about that structure. Check with your TA to be certain that you
haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a particular stage of
development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
NOTE! NOT ALL OF THESE STRUCTURES/TISSUES ARE PRESENT IN BOTH THE 4mm AND 7mm
STAGE. PART OF YOUR RESPONSIBILITY FOR THESE TWO STAGES IS TO FIGURE OUT WHAT
CHANGES.
Nervous System
Central Nervous System
____ tuberculum posterious
____ prosencephalon
(=forebrain)
____ prosocoel
____ telencephalon
____ telocoel
____ diencephalon
____ diocoel
____ mesencephalon
(=midbrain)
____ mesocoel (=aqueduct of
Sylvius)
____ infundibulum
(=neurohypophysis)
____ rhombencephalon
(=hindbrain)
____ rhombocoel
____ spinal cord
Digestive System
____ Foregut
____ oral plate
____ stomodeum
____ pharynx
____ liver diverticulum
____ thyroid rudiment
____ proctodeum (=anus)
____ Midgut
____ yolk endoderm
____ Hindgut
____ yolk endoderm
48
Respiratory System
____ external gills
4 – 7 mm Frog Embryo
Page 2 of 3
Nervous System
Digestive System
Respiratory System
Urogenital System
Pharyngeal Structures
Urinary System
____ pronephros
____ pronephric tubules
____ pronephric duct
(=Wolffian duct,
archinephric duct)
____ mesomere (= nephrotome)
____ visceral (=pharyngeal,
=branchial) arch
____ visceral (=pharyngeal,
=branchial) cleft/groove
____ visceral (=pharyngeal,
=branchial) pouch
____ mandibular arch
____ hyoid arch
____ hyomandibular pouch
____ hyomandibular cleft
____ epiphysis (=pineal body)
____ sensory retina
____ presumptive pigmented retina
____ hypophysis (=pituitary body)
____ optic stalk
____ optic vesicle (maybe 4mm)
____ optic cup (7mm)
____ opticoel
____ *choroid (optic) fissure
Peripheral Nervous System
____ olfactory pit
____ otic vesicle
____ lens placode/vesicle
Circulatory System
Arterial (7mm)
____ aorta (dorsal, ventral)
____ aortic arch
Venous
____ vitelline veins
Cardiac
____ heart
____ pericardial coelom
____ pericardium
____ atrium (7mm)
____ ventricle (7mm)
____ conus arteriosus (=bulbus
cordis,=bulbus
arteriosus) (7mm)
____ myocardium
____ endocardium
Genital System
(nothing obvious yet)
49
4 – 7 mm Frog Embryo
Page 3 of 3
Skeleto-muscular System
____ notochord
____ hypochordal
(subnotochordal) rod
____ epimere (=somite)
____ hypomere (=lateral plate
mesoderm)
____ dermatome
____ myotome
____ sclerotome
Endocrine System
____ epiphysis (=pineal gland)
____ hypophysis (=pituitary
gland)
____ infundibulum of
diencephalon
(=neurohypophysis,
=posterior pituitary)
____ Rathke’s pocket/pouch
(=adenohypophysis,
=anterior pituitary
____ thyroid
50
Miscellaneous Structures
____ adhesive gland (=ventral
sucker)
____ head mesenchyme
____ epidermis
____ coelom
Laboratory Identification List
10 mm Frog Embryo
Page 51 of 90
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you cannot point,
but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so labeled are at
exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be identified on your
slides, but you must still know the pertinent information about that structure. Check with your TA to be certain that you
haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a particular stage of
development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
Ectodermal Derivatives
Central Nervous System
____ Prosencephalon
____ telencephalon
____ telocoel
____ olfactory nerve
____ diencephalon
____ diocoel
____ epiphysis
____ infundibulum (=neurohypophysis)
____ optic nerve
____ optic cup
____ optic chiasma
____ optic recess (groove)
____ torus transversus
____ Mesencephalon
____ mesocoel (=aqueduct of Sylvius)
____ Rhombencephalon
____ rhombocoel
____ metencephalon
____ metacoel
____ myelencephalon
____ myelocoel
____ posterior choroid plexus (neural portion
only)
____ Spinal Cord
____ dorsal root
____ dorsal root (spinal) ganglion
____ ventral root
Special Sense Organs
____ Eye
____ lens
____ pigmented retina
____ sensory retina
____ cornea
____ anterior chamber
____ vitreous chamber
____ optic cup
____ optic nerve (cranial nerve II)
____ Ear
____ saccule (=sacculus)
____ *semicircular canal
____ utricle (=utriculus)
____ endolymphatic duct
____ otic vesicle
____ Nose
____ nasal cavity
____ olfactory nerve (cranial nerve I)
____ nares
____ internal nares
____ external nares
Miscellaneous Ectodermal Derivatives
____ stomodeum
____ proctodeum
____ tuberculum posterious
____ *spiracle
51
Laboratory Identification List
10 mm Frog Embryo
Page 2 of 3
Ectodermal Derivatives
Central Nervous System
Special Sense Organs
____ ependymal layer
____ mantle layer
____ marginal layer
____ spinal canal
____ gill (internal)
____ *gill raker
____ opercular cavity
____ *velar plate
____ tongue
____Pituitary Gland
____ adenohypophysis (from Rathke’s pocket)
____ neurohypophysis (infundibulum of
diencephalon)
Endodermal Derivatives
Digestive, Respiratory & Endocrine Organs
____ pharynx
____ esophagus
____ stomach
____ intestine
____ liver
____ lung buds
____ thyroid
____ trachea
____ hyomandibular pouches (What do these tissues form in the adult?)
Mesodermal Derivatives
Circulatory System
Skeleto-muscular System
Venous System
____ posterior (=caudal) cardinal veins
____ anterior (=cranial) cardinal veins
____ common cardinal veins (ducts of Cuvier)
Epimere (=somite)
____ dermatome
____ myotome
____ sclerotome
Cardiac System (Heart)
____ sinus venosus
____ atrium (=auricle)
____ ventricle
____ bulbus arteriosus (=conus arteriosus,
=bulbus cordis, =conotruncus)
____ truncus arteriosus [also part of arterial
system]
____ pericardium
Mesomere (=nephrotome)
____ mesonephros
____ mesonephric duct (=Wolffian duct;
formerly pronephric duct = archinephric
duct)
52
Laboratory Identification List
10 mm Frog Embryo
Page 3 of 3
Mesodermal Derivatives
Circulatory System
____ pericardial cavity (coelom)
____ endocardium
____ myocardium
____ trabeculae carnae
Arterial System
____ ventral aorta (=truncus arteriosus)
____ dorsal aorta
____ internal carotid artery
Skeleto-muscular System
Hypomere (=lateral plate mesoderm)
____ splanchnic mesoderm
____ somatic mesoderm
____ coelom
____ mesentery
____ pericardium
____ pericardial cavity
____ peritoneum
____ peritoneal cavity
____ lymph sinus
Mesodermal Derivatives (continued)
Skeleto-muscular System (continued)
____ mesenchyme
____ cranial cartilage
____ visceral arch #1 (mandibular arch)
____ visceral arch #2) (hyoid arch)
____ visceral arch #3
____ visceral arch #4
53
Laboratory Identification List
Cranial Nerves and Ganglia (page 1 of 4)
In this course the twelve pairs of vertebrate cranial nerves are studied only in the chick and pig
embryos, where they are seen to best advantage. (Several, however, are indicated in the 10 mm Frog
labeled transverse sections.) Cranial ganglia are associated with cranial nerves V, VII, VIII, IX, X,
and XI, although the latter (XI) is obscure and will not be found easily.
Cranial nerves and associated ganglia originate from neural ectoderm of brain and spinal cord, from
neural crest cells, and from dorsolateral and epibranchial placodal ectoderm. Some cranial nerves are
purely sensory (afferent), some purely motor (efferent), and some mixed. Sensory fibers are usually
generated by cells from neural crest and/or dorsolateral placodal ectoderm, although epibranchial
placodal ectoderm forms some sensory fibers associated with certain visceral (pharyngeal) pouches.
Motor fibers are usually derived from neural ectoderm of the central nervous system (somatic efferent
and first order autonomic efferent fibers), but may also be formed by neural crest cells (second order
autonomic efferent fibers). Cranial nerves I (olfactory), II (optic), and VIII (auditory) are referred to
as “special sensory” because of the great amount of sensory input they provide to the central nervous
system.
The information in the following three tables should help you understand the basic relationships
between cranial nerves, cranial ganglia, and their developmental origins.
Locate as many of the cranial nerves and their ganglia as possible. You are responsible for answering
the following questions:
Which cranial nerves are sensory? Which are motor? Which are mixed (sensory and motor)?
What does each of the cranial nerves innervate?
Which cranial nerves are associated with ganglia? What are the names of those ganglia?
What are the developmental origins of the cranial nerves and ganglia?
A traditional mnemonic (memory aid) for the order of the twelve cranial ganglia of vertebrates is:
“On Old Olympus’ Towering Top A Finn And German Vaulted And Hopped”
(There is no scientific meaning to this other than word order. We tend to remember ridiculous things
easier than, e.g., the order of the vertebrate cranial nerves.)
From anterior to posterior, the twelve cranial nerves of vertebrates are:
Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens,
Facial, Acoustic, Glossopharyngeal, Vagus, (Spinal) Accessory, Hypoglossal
Compare the order of the first letter of each word in the mnemonic with that of the anterior to
posterior sequence of cranial nerves.
54
Laboratory Identification List
Cranial Nerves and Ganglia (page 2 of 4)
Table 1: The Vertebrate Cranial Nerves & Associated Ganglia
Mnemonic
No.
On
I
Cranial
Nerve
Olfactory
Old
II
Optic
Function
special
sensory
special
sensory
Brain
Association
telencephalon
Associated Ganglia
Study in:
chick (72,
96), pig
chick (48,
diencephalon
72, 96),
Olympus’
III
Oculomotor
motor
mesencephalon
Towering
IV
Trochlear
motor
mesencephalon
Top
V
Trigeminal
mixed
myelencephalon
pig
chick (72,
96), pig
Gasserian
(=semilunar)
chick (48,
chick (72,
96), pig
chick (72,
96), pig
chick (72,
96), pig
A
VI
Abducens
motor
myelencephalon
Finn
VII
Facial
mixed
myelencephalon
geniculate
And
VIII
Acoustic
myelencephalon
vestibular & acoustic
German
IX
Glossopharyngeal
special
sensory
mixed
myelencephalon
superior (proximal) &
inferior (distal or
petrosal)
Vaulted
X
Vagus
mixed
myelencephalon
jugular (proximal) &
nodose (distal)
(Spinal
Accessory)
motor
myelencephalon
Froriep’s (degenerate
occipital ganglia)
Hypoglossal
motor
72, 96),
pig
chick (72,
96), pig
Accessory
And
Hopped
XI
XII
chick
pig
myelencephalon
chick (96),
pig
© S.R. Haley & S.C. Kempf, 7/25/11
(96),
Note: With respect to cranial ganglia, the terms superior (or proximal) and inferior (or distal)
indicate position on the cranial nerve relative to the central nervous system (brain and spinal
cord). e.g., The jugular ganglion on the Vagus nerve (X) is closer (proximal) to the central
nervous system than is the distal nodose ganglion.
55
Laboratory Identification List
Cranial Nerves and Ganglia (page 3 of 4)
Table 2: Origin & Distribution of Cranial Nerves
S=
SS =
M=
No.
Cranial
Nerve
Sensory
A=
Special Sensory 1’ =
Motor (somatic) 2” =
*Function
I
Olfactory
SS
II
Optic
SS
*Legend
Autonomic (motor)
First order autonomic
Second order autonomic
Large Case =
small case =
*Developmental Origin
Distribution
olfactory placode
olfactory bulb of
telencephalon
sensory retina
(lateral diencephalon)
III
Oculomotor
M, a
1 extraocular eye
muscle
visceral arch I
derivatives
M
ventrolateral mesencephalon
V
Trigeminal
S, m
neural crest & epibranchial placode (S);
ventrolateral myelencephalon (m)
VI
Abducens
M
ventrolateral myelencephalon
S, M, a
neural crest & epibranchial placodes (S,
2”a);
ventrolateral metencephalon (M, 1’a)
Acoustic
VIII
IX
X
(Auditory)
SS
Glossopharyngeal
S, M, a
Vagus
S, M, A
Accessory
otic placode
neural crest (S, superior ganglion; 2”a),
epibranchial placode (S, petrosal
ganglion);
ventrolateral myelencephalon (M, 1’a)
neural crest (S, jugular ganglion; 2”A),
epibranchial placode (S, nodose
ganglion);
ventrolateral myelencephalon (M, 1’A)
XI
(Spinal
Accessory)
M, a
myelencephalon & spinal cord (M, 1’a);
neural crest (2”a)
XII
Hypoglossal
M
ventrolateral myelencephalon
56
Study
in:
chick
(72, 96),
pig
chick
(72, 96)
chick
intraocular & 4
extraocular eye
muscles
Trochlear
Facial
visual centers of
brain
ventrolateral mesencephalon (M, 1’a);
neural crest (2” a)
IV
VII
major component
minor component
1 extraocular eye
muscle
visceral arch II
derivatives
cochlea &
vestibular
apparatus
visceral arch III
derivatives
(72, 96),
pig
chick
(48, 72,
96), pig
chick
(72, 96),
pig
chick
(72, 96),
pig
chick
(72, 96),
pig
visceral arches IV
& VI derivatives;
heart, visceral
organs
visceral arch IV
derivatives, neck,
shoulder
muscles of tongue
chick
(72, 96),
pig
Chick
pig
(72),
Chick
(96), pig
Laboratory Identification List
Cranial Nerves and Ganglia (page 4 of 4)
Table 3: Origin of Cranial Ganglia
Neurons whose cell bodies lie in cranial ganglia are sensory in function.
No.
Cranial
Nerve
Function
I
Olfactory
II
Optic
special
sensory
special
sensory
III
IV
Oculomotor
Trochlear
motor
motor
Associated
Ganglion
Ganglion Origin
Study in:
chick (72,
96), pig
chick (48,
72, 96),
pig
chick (72,
96), pig
none
none
none
none
V
Trigeminal
mixed
Gasserian
(=semilunar)
VI
Abducens
motor
none
VII
Facial
mixed
geniculate
VIII
Acoustic
special
sensory
vestibuloacoustic
otic placode
chick (72,
96), pig
IX
Glossopharyngeal
mixed
proximal (superior)
& distal (petrosal)
neural crest (proximal) &
epibranchial placode (distal)
chick (72,
96), pig
X
Vagus
mixed
proximal (jugular)
& distal (nodose)
neural crest (jugular) &
epibranchial placode
(nodose)
chick (72,
96), pig
Froiep’s ganglia are
degenerate occipital spinal
ganglia (neural crest)
chick (72,
96), pig
XI
Accessory
motor
Froiep’s
XII
Hypoglossal
motor
none
57
neural crest &
epibranchial placodes
chick (48,
72, 96),
pig
neural crest &
epibranchial placode
chick (72,
96), pig
chick (72,
96), pig
Laboratory Identification List
NOTE: Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you
cannot point, but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so
labeled are at exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be
identified on your slides, but you must still know the pertinent information about that structure. Check with your TA to be
certain that you haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a
particular stage of development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
18 and 24 hr Chick Embryo
Extraembryonic…
____ area pellucida
____ area opaca
____ yolk
Embryonic…
____ primitive streak
____ primitive knot (=Hensen’s
node)
____ primitive groove
____ primitive pit
____ primitive fold
Both
24 hr Chick Embryo (page 1 of 2)
Extraembryonic…
____ area opaca vasculosa
____ area opaca vitellina
____ proamnion
____ subcephalic pocket
____ subgerminal cavity
____ hypoblast
____ yolk sac
Embryonic…
____ epidermis
____ head
____ head mesenchyme
____ primitive streak
____ primitive knot (=Hensen’s
node)
____ primitive groove
____ primitive pit
____ primitive fold
Nervous System
____ neural ectoderm
____ neural folds
____ neural plate
____ neural tube
____ neural groove
____ neurocoel
____ prosencephalon
____ prosocoel
58
Both
The following must be identified as
“embryonic” or extraembryonic”
when you identify them on exams.
____ coelom (extraembryonic
coelom = exocoel)
____ ectoderm (non-neural)
____ mesoderm
____ endoderm
____ epiblast
____ hypoblast
____ somatic mesoderm
____ somatopleure
____ splanchnic mesoderm
____ splanchnopleure
Laboratory Identification List
24 hr Chick Embryo (page 2 of 2)
Extraembryonic…
Embryonic…
Digestive System
____ anterior(cranial)
intestinal portal
____ foregut
____ midgut
Skeleto-muscular System
____ notochord
____ somite = epimere
____ lateral plate mesoderm
(=hypomere)
59
Both
Laboratory Identification List
33 hr Chick Embryo (page 60 of 90)
NOTE: You should begin thinking about how the embryo’s body is delimited from underlying extraembryonic tissues and
yolk mass, and how the somatopleure and splanchnopleure act to form the various extraembryonic membranes. This is a
dynamic process that occurs in three dimensions. You are looking at essentially two-dimensional sections of an “instant”
in this process. Part of your challenge is to analyze how the chick embryo’s body and extraembryonic structures are
forming by putting together your observations of the various sections (i.e., 18, 24, 33, 48, 72, 96 hr) that you examine.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
Extraembryonic…
____ amnion
____ amniotic (seroamniotic)
folds
____ area opaca vasculosa
____ area opaca vitellina
____ area pellucida
____ blood island
____ chorion (=serosa)
____ proamnion
____ primitive streak
____ primitive knot (=Hensen’s
node)
____ subcephalic pocket
____ subgerminal cavity
____ yolk sac
Embryonic…
____ neural ectoderm
____ epidermis
____ head
____ head mesenchyme
Nervous & Sensory System
____ alar plate
____ basal plate
____ diencephalon
____ diocoel
____ infundibulum
____ mesencephalon
____ mesocoel (aqueduct of
Sylvius)
____ metencephalon
____ metacoel
____ myelencephalon
____ myelocoel
____ neural crest
____ neural ectoderm
____ neural folds
____ neural plate
____ neural tube
____ neurocoel
____ neuromere
____ neuropore (anterior)
____ opticoel
60
Both
The following must be
identified as “embryonic” or
extraembryonic” when you
identify them on exams.
____ coelom (extraembryonic
coelom = exocoel)
____ ectoderm (non-neural)
____ mesoderm
____ endoderm
____ epiblast
____ hypoblast
____ somatic mesoderm
____ somatopleure
____ splanchnopleure
____ splanchnic mesoderm
Laboratory Identification List
33 hr Chick Embryo (page 61 of 90)
Extraembryonic…
Embryonic…
Both
Nervous & Sensory System
(continued)
____ optic stalk
____ optic vesicle
____ prosencephalon
____ prosocoel
____ sinus rhomboidalis
____ spinal cord
Digestive System
____ anterior intestinal portal
____ midgut
____ oral plate
____ pharynx (=foregut)
Circulatory System
____ endocardium
____ dorsal aortic roots
____ heart
____ myocardium
(epimyocardium)
____ pericardium
____ pericardial cavity
____ ventral aorta
(truncus arteriosus)
____ ventral aortic roots
Skeleto-muscular System
____ notochord
____ somite = epimere
____ lateral plate
mesoderm
(=hypomere)
61
Circulatory System
____ omphalomesenteric veins
Laboratory Identification List
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you cannot point,
but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so labeled are at
exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be identified on your
slides, but you must still know the pertinent information about that structure. Check with your TA to be certain that you
haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a particular stage of
development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
48 hr Chick Embryo (page 62 of 4
Extraembryonic…
____ amnion
____ seroamniotic (amniotic)
folds
____ amniotic cavity
____ *area opaca vasculosa
____ *area opaca vitellina
____ area pellucida
____ blood island
____ chorion (=serosa)
____ lateral limiting sulcus
____ proamnion
____ seroamniotic
junction/raphe
____ subcephalic pocket
____ subgerminal cavity
____ yolk sac
Embryonic…
____ neural ectoderm
____ epidermis
____ cranial (cephalic) flexure
____ head
____ head mesenchyme
____ hyomandibular cleft
____ lateral limiting sulcus
____ tailbud
____ visceral grooves
(= clefts)
Nervous & Sensory System
____ alar plate
____ basal plate
____ choroid (optic) fissure
____ diencephalon
____ diocoel
____ dorsal isthmus (of brain)
____ infundibulum
(of diencephalon)
____ mesencephalon
____ mesocoel (=aqueduct of
Sylvius)
____ metacoel
____ metencephalon
____ myelencephalon
____ myelocoel
____ neural crest
62
Both
The following must be
identified as “embryonic” or
extra-embryonic” when you
identify them on exams.
____ coelom (extraembryonic
coelom = exocoel)
____ ectoderm (non-neural)
____ mesoderm
____ endoderm
____ epiblast
____ hypoblast
____ non-neural ectoderm
____ somatic mesoderm
____ somatopleure
____ splanchnopleure
____ splanchnic mesoderm
Laboratory Identification List
48 hr Chick Embryo (page 2 of 4)
Extraembryonic…
Embryonic…
____ neural ectoderm
____ neural tube
____ neurocoel
____ neuromere
____ neuropore (anterior)
____ opticoel
____ optic stalk
____ optic cup
____ lens vesicle
____ otic (auditory) cup
(= forming
otic/auditory vesicle)
____ pigmented retina
(presumptive)
____ sensory retina
(presumptive)
____ prosencephalon
____ prosocoel
____ rhombencephalon
____ rhombocoel
____ spinal cord
____ telencephalon
____ telocoel
____ tuberculum posterius
Digestive System
____ anterior intestinal portal
____ hyomandibular pouch
____ intestinal portal (anterior)
____ *intestinal portal
____ midgut
____ oral plate
____ pharynx (=foregut)
____ pre-oral gut (=Seessel’s
pocket)
____ *primordium of liver
diverticulum
____ stomodeum
____ visceral pouches
63
Both
Laboratory Identification List
48 hr Chick Embryo (page 3 of 4)
Extraembryonic…
Embryonic…
Both
Respiratory System
____* laryngotracheal groove
Circulatory System
____ anterior (cranial) cardinal
vein
____ aortic arches (1, 2, 3)
____ aortic roots (dorsal,
ventral)
____ atrium
____ cardinal veins (anterior)
____ cardinal veins (posterior)
____ cardinal veins (common;
=ductus cuvieri)
____ bulbus arteriosus (=conus
arteriosus, =bulbus
cordis, =conotruncus)
____ dorsal aorta
____ endocardium
____ heart
____ *intersegmental artery
____ myocardium
____ pericardium
____ pericardial cavity
____ sinus venosus
____ truncus arteriosus
(=ventral aorta)
____ ventricle
Urogenital System
____ mesonephric (=Wolffian)
ducts
64
Circulatory System
____ vitelline
(=omphalomesenteric) arteries
____ vitelline
(=omphalomesenteric) veins
Laboratory Identification List
48 hr Chick Embryo (page 4 of 4)
Extraembryonic…
Embryonic…
Skeleto-muscular System
____ visceral (=brnachial)
arches (1,2,3)
____ dermatome
____ hyoid arch
____ hypomere (=lateral plate)
____ lateral plate mesoderm
(=hypomere)
____ mandibular arch
____ maxillary process
____ mesomere (=nephrotome
=intermediate
mesoderm)
____ *myocoel
____ myotome
____ notochord
____ sclerotome
____ somite = epimere
Endocrine System
____ Rathke’s pouch/pocket
____ thyroid primordium
65
Both
Laboratory Identification List
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you cannot point,
but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so labeled are at
exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be identified on your
slides, but you must still know the pertinent information about that structure. Check with your TA to be certain that you
haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a particular stage of
development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
72 hr Chick Embryo (page 66 of 90)
Extraembryonic…
____ allantois
____ amnion
____ seroamniotic (amniotic)
folds
____ amniotic cavity
____ area opaca vasculosa
____ *area opaca vitellina
____ area pellucida
____ blood island
____ chorion (=serosa)
____ lateral limiting sulcus
____ proamnion
____ seroamniotic
raphe/junction
____ subcaudal pocket
____ subcephalic pocket
____ subgerminal cavity
____ yolk sac
Embryonic…
____ apical ectodermal ridge
____ visceral (=branchial
=pharyngeal) cleft/groove
(1,2,3,4)
____ epidermis
____ cranial (=cephalic) flexure
____ *cervical flexure
____ head
____ head mesenchyme
____ hyomandibular cleft
____ lateral body fold
____ lateral limiting sulcus
____ limb buds (wing, leg)
____ neural ectoderm
____ peritoneal cavity
____ tailbud
____ *torsion (dextral)
____ ventral mesentery
Nervous & Sensory System
____ alar plate
____ acoustico-facialis nerve
(CN #7 & #8)
____ basal plate
____ cerebral hemisphere
66
Both
The following must be
identified as “embryonic” or
extra-embryonic” when you
identify them on exams.
____ coelom (extraembryonic
coelom = exocoel)
____ ectoderm (non-neural)
____ mesoderm
____ endoderm
____ non-neural ectoderm
____ somatic mesoderm
____ somatopleure
____ splanchnopleure
____ splanchnic mesoderm
Laboratory Identification List
72 hr Chick Embryo (page 2 of 90)
Extraembryonic…
Embryonic…
Nervous & Sensory System
____ choroid (optic) fissure
____ cranial ganglion
____ cranial nerve
____ diencephalon
____ diocoel
____ dorsal isthmus (of brain)
____ endolymphatic duct
____ ganglion (acousticofacialis, CN #7 & #8)
____ ganglion (Gasserian, CN
#5)
____ infundibulum
(of diencephalon)
____ lens epithelium
____ lens fibers
____ lens vesicle (lens)
____ mesencephalon
____ mesocoel (=aqueduct of
Sylvius)
____ metacoel
____ metencephalon
____ myelencephalon
____ myelocoel
____ neural crest
____ neural ectoderm
____ neural tube
____ neurocoel
____ neuromere
____ oculomotor nerve (CN #3)
____ olfactory(nasal) pit
(external nares)
____ optic nerve (CN #2)
____ opticoel
____ optic stalk
____ optic cup
____ otic (=auditory, =acoustic)
vesicle
67
Both
Laboratory Identification List
72 hr Chick Embryo (page 3 of 90)
Extraembryonic…
Embryonic…
Nervous & Sensory System
____ pigmented retina
(presumptive)
____ posterior choroid plexus
____ prosencephalon
(telencephalon +
diencephalon)
____ prosocoel
____ rhombencephalon
(metencephalon +
myelencephalon)
____ rhombocoel
____ sensory retina
(presumptive)
____ spinal cord
____ spinal ganglia
____ telencephalon
____ telocoel
____ trigeminal nerve (CN #5)
____ tuberculum posterius
Digestive System
____ anterior (=cranial)
intestinal portal
____ visceral, (=branchial
=pharyngeal) pouch
(1,2,3,4)
____ cloaca
____ duodenum
____ esophagus
____ gastrohepatic ligament
____ hindgut
____ hyomandibular pouch
____ intestine
____* laryngotracheal groove
____ liver
____ liver diverticulum
____ mesentery (dorsal,
ventral)
____ mesogaster(dorsal,
ventral)
____ midgut
68
Both
Laboratory Identification List
72 hr Chick Embryo (page 4 of 90)
Extraembryonic…
Embryonic…
Both
Digestive System
____ mouth
____ omentum (greater, lesser)
____ peritoneal cavity
____ pharynx (=foregut)
____ posterior(caudal)
intestinal portal
____ post-anal gut (tail gut)
____ pre-oral gut (=Seessel’s
pocket)
____ stomach
____ stomodeum
____ visceral pouches
Respiratory System
____ *glottis (presumptive)
____ laryngotracheal groove
____ lung buds
____ pleural cavity
____ trachea
Circulatory System
____ aorta (dorsal)
____ aortic arch (1,2,3,4,*6)
____ aortic roots (dorsal,
ventral)
____ atrium
____ cardinal veins (anterior,
cranial = jugular veins)
____ cardinal veins (posterior,
caudal)
____ cardinal veins (common;
=ductus cuvieri)
____ caudal artery
69
Circulatory System
____ allantoic vein
____ vitelline
(=omphalomesenteric) artery
____ vitelline
(=omphalomesenteric)
vein
Laboratory Identification List
72 hr Chick Embryo (page 5 of 90)
Extraembryonic…
Embryonic…
Circulatory System
____ bulbus arteriosus (=conus
arteriosus, =bulbus
cordis, =conotruncus)
____ ductus venosus
____ endocardium
____ heart
____ internal carotid arteries
____ intersegmental artery
____ myocardium
____ pericardium
____ pericardial cavity
____ sinus venosus
____ truncus arteriosus
(=ventral aorta, =ventral
aortic sac)
____ ventricle
Urogenital System
____ genital ridge
____ mesonephric (Wolffian)
duct
____ mesonephric tubule
____ mesonephros
____ nephrotome (mesomere =
intermediate mesoderm)
Skeleto-muscular System
____ visceral (=branchial,
=pharyngeal) arches
(1,2,3,4)
____ dermatome
____ epimere
____ hyoid arch
____ lateral plate mesoderm
(hypomere)
____ mandibular arch
____ maxillary process
____ *myocoel
____ myotome
70
Both
Laboratory Identification List
72 hr Chick Embryo (page 6 of 90)
Extraembryonic…
Embryonic…
Skeleto-muscular System
____ notochord
____ sclerotome
____ septum transversum
____ somite (=epimere)
____ visceral groove
Endocrine System
____ epiphysis (pineal gland)
____ Rathke’s pocket/pouch
____ thyroid primordium
71
Both
Laboratory Identification List
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you cannot point,
but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so labeled are at
exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be identified on your
slides, but you must still know the pertinent information about that structure. Check with your TA to be certain that you
haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a particular stage of
development.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
96 hr Chick Embryo (page 72 of 90)
Extraembryonic…
____ allantois
____ allantoic vesicle
____ amnion
____ seroamniotic (amniotic)
folds
____ amniotic cavity
____ area opaca vasculosa
____ *area opaca vitellina
____ area pellucida
____ blood island
____ chorion (=serosa)
____ lateral limiting sulcus
____ proamnion
____ seroamniotic
raphe/junction
____ subcaudal pocket
____ subcephalic pocket
____ subgerminal cavity
____ yolk sac
Embryonic…
____ apical ectodermal ridge
____ visceral (=branchial,
=pharyngeal)
cleft/groove (1,2,3,4)
____ epidermis
____ cranial (=cephalic) flexure
____ cervical flexure
____ head
____ head mesenchyme
____ hyomandibular cleft
____ lateral body fold
____ lateral limiting sulcus
____ limb bud (wing, leg)
____ neural ectoderm
____ peritoneal cavity
____ tailbud
____ tail fold
____ *torsion (dextral)
____ ventral mesentery
Nervous & Sensory System
____ acoustico-facialis nerve
(CN #7 & #8)
____ alar plate
____ basal plate
____ brain ventricles (1,2,3,4)
____ cerebellum (presumptive)
____ cerebral hemisphere
(cerebrum)
72
Both
The following must be
identified as “embryonic” or
extra-embryonic” when you
identify them on exams.
____ coelom (extraembryonic
coelom = exocoel)
____ ectoderm (non-neural)
____ mesoderm
____ endoderm
____ somatic mesoderm
____ somatopleure
____ splanchnopleure
____ splanchnic mesoderm
Laboratory Identification List
96 hr Chick Embryo (page 2 of 90)
Extraembryonic…
Embryonic…
Nervous & Sensory System
____ choroid (optic) fissure
____ choroid plexus (posterior)
____ cranial ganglion
____ cranial nerve
____ diencephalon
____ diocoel
____ dorsal isthmus (of brain)
____ endolymphatic duct
____ facial nerve (cranial nerve
VII)
____ ganglion (acousticofacialis, CN #7 & #8)
____ ganglion (Gasserian, CN
#5)
____ ganglion (petrosal, CN
#9))
____ ganglion (nodose, CN
#10)
____ glossopharyngeal nerve
(CN #9)
____ infundibulum (of
diencephalon)
____ lens epithelium
____ lens fibers
____ lens vesicle
____ *medulla oblongata
(presumptive)
____ mesencephalon
____ mesocoel (=aqueduct of
Sylvius)
____ metacoel
____ metencephalon
____ myelencephalon
____ myelocoel
____ neural crest
____ neural tube
____ neurocoel
____ neuromere
73
Both
Laboratory Identification List
96 hr Chick Embryo (page 3 of 90)
Extraembryonic…
Embryonic…
Nervous & Sensory System
____ oculomotor nerve (CN #3)
____ olfactory(nasal) pit
____ opticoel
____ optic nerve (CN #2)
____ optic stalk
____ optic cup
____ otic (=auditory, =acoustic)
vesicle
____ pigmented retina
(presumptive)
____ posterior choroid plexus
____ prosencephalon
____ prosocoel
____ rhombencephalon
____ rhombocoel
____ sensory retina
(presumptive)
____ spinal cord
____ spinal ganglion
____ spinal nerve
____ telencephalon
____ telocoel
____ trigeminal nerve (CN #5)
____ tuberculum posterius
Digestive System
____ anterior (=cranial)
intestinal portal
____ visceral (=branchial,
=pharyngeal) pouch
(1,2,3,4)
____ cloaca
____ cloacal membrane
____ duodenum
____ esophagus
74
Both
Laboratory Identification List
96 hr Chick Embryo (page 4 of 90)
Extraembryonic…
Embryonic…
Digestive System
____ gastrohepatic ligament
____ hindgut
____ hyomandibular pouch
(eustachian tube,
presumptive)
____ intestine
____* laryngotracheal groove
____ liver
____ liver diverticulum
____ mesentery (dorsal, ventral)
____ mesoesophagus
____ mesogaster(dorsal,
ventral)
____ midgut
____ mouth
____ omentum (greater, lesser)
____ peritoneal cavity
____ pharynx (=foregut)
____ posterior(caudal)
intestinal portal
____ post-anal gut
____ pre-oral gut (=Seessel’s
pocket)
____ stomach
____ stomodeum
____ tailgut (postanal gut)
Respiratory System
____ *glottis (presumptive)
____ *laryngotracheal groove
____ lung buds (primary
bronchi)
____ pleural cavity
____ trachea
75
Both
Laboratory Identification List
96 hr Chick Embryo (page 5 of 90)
Extraembryonic…
Embryonic…
Circulatory System
____ dorsal aorta
____ aortic arches (1,2,3,4,6)
____ aortic roots (dorsal,
ventral)
____ atrium
____ cardinal veins (anterior,
cranial)
____ cardinal veins (posterior,
caudal)
____ cardinal veins (common;
=ductus cuvieri)
____ caudal artery
____ conotruncus (=bulbous
arteriosus,= conus
arteriosus,= bulbous
cordis)
____ ductus venosus
____ endocardium
____ heart
____ trabeculae carnae
____ *iliac artery
____ internal carotid arteries
____ intersegmental arteries
____ superior mesenteric artery
____ myocardium
____ pericardium
____ pericardial cavity
____ sinus venosus
____ truncus arteriosus
(=ventral aorta, =aortic
sac)
____ ventricle
76
Both
Circulatory System
____ vitelline
(=omphalomesenteric) artery
____ vitelline
(=omphalomesenteric)
vein
Laboratory Identification List
96 hr Chick Embryo (page 6 of 90)
Extraembryonic…
Embryonic…
Urogenital System
____ genital ridge
____ glomerulus
____ mesonephric (Wolffian)
duct
____ mesonephric tubule
____ mesonephros
____ nephrotome (mesomere =
intermediate mesoderm)
Skeleto-muscular System
____ visceral (=branchial,
=pharyngeal) arches
(1,2,3,4)
____ dermatome
____ hyoid arch
____ hyomandibular cleft
____ lateral plate mesoderm
(hypomere)
____ mandibular arch
____ maxillary process
____ *myocoel
____ myotome
____ notochord
____ sclerotome
____ septum transversum
____ somite (epimere)
Endocrine System
____ epiphysis (pineal gland)
____ *hypophysis (pituitary
gland)
____ Rathke’s pocket
____ thyroid primordium
77
Both
Laboratory Identification List
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you cannot point,
but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so labeled are at
exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be identified on your
slides, but you must still know the pertinent information about that structure. Check with your instructor to be certain that
you haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a particular stage of
development. Recall that the first time a term is added to the list, it is italicized, but not subsequently. As you progress to
later stages, you will be able to identify the new terms easily by this style.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
6 mm Pig Embryo (page 1 of 5)
Extraembryonic…
____ allantois
____ amnion
____ amniotic cavity
____ chorion* (serosa)
____ seroamniotic
junction/raphe
____ subcaudal pocket
____ subcephalic pocket
Embryonic…
Both
____ epidermis
____ flexure (cephalic, cranial)
____ flexure (cervical)
____ *flexure (caudal)
____ head
____ head mesenchyme
____ limb bud
____ mesoderm
____ tail bud
____ tail fold
____ visceral (pharyngeal)
cleft/groove (1, 2, 3, 4)
____ visceral (pharyngeal)
pouch (1, 2, 3, 4)
____ …coelom (extraembryonic
coelom = exocoel)
____ …ectoderm
____ ...endoderm
____ …mesoderm
____ allantoic stalk
____ coelom
____ ectoderm
____ endoderm
____ epidermis
____ mesoderm
____ somatopleure
____ splanchnopleure
Nervous & Sensory System
(Note: CN = Cranial Nerve)
____ abducens nerve (CN 6)
____ accessory nerve (CN 11)
____ accessory ganglion (next
to CN 11, but really part
of CN 10)
____ acoustic ganglion (CN 8)
____ alar(roof) plate
____ anterior chamber (ocular)
____ auditory nerve (CN 8)
____ auditory (otic) vesicle
78
Extraembryonic…
6 mm Pig Embryo (page 2 of 5)
Embryonic…
Nervous & Sensory System
____ basal (floor) plate
____ choroid fissure
____ diencephalon
____ diocoel
____ facial nerve (CN #7)
____ geniculate ganglion(CN #7)
____ glossopharyngeal nerve
(CN #9)
____ hypoglossal nerve (CN #12)
____ jugular ganglion (CN #10)
____ lens
____ mesencephalon
____ mesocoel (aqueduct of
Sylvius)
____ metacoel
____ metencephalon
____ myelencephalon
____ myelocoel
____ nodose ganglion (CN #10)
____ oculomotor nerve (CN #3)
____ olfactory bulb
____ olfactory nerve (CN #1)
____ olfactory placode
____ optic cup
____ optic nerve (CN #2)
____ optic stalk
____ optic vesicle
____ otic cup/vesicle
____ petrosal ganglion (CN #9)
____ posterior chamber (ocular)
____ prosocoel
____ retina (pigmented, sensory)
____ rhombencephalon
____ rhombocoel
____ semilunar (Gasserian)
ganglion (CN #5)
____ spinal cord
____ spinal (dorsal root)
ganglion
____ spinal nerve (dorsal, ventral
roots)
____ superior ganglion (CN #9)
____ telencephalon
____ telocoel
____ vagus nerve (CN 10
79
Both
6 mm Pig Embryo (3 of 5)
Extraembryonic…
Embryonic…
Digestive System
____ cloaca
____ cloacal plate (membrane)
____ colon (large intestine)
____ common bile duct (ductus
choledochus)
____ ductus choledochus
(common bile duct)
____ duodenum
____ esophagus
____ falciform ligament
____ gall bladder
____ glottis
____ hepatic sinusoid
____ hindgut
____ liver diverticulum
____ mesocolon
____ mesoduodenum
____ omentum (greater, lesser)
____ pancreas (dorsal, ventral)
____ peritoneal cavity
____ pharynx
____ Seessel’s pocket (pre-oral
gut)
____ small intestine
____ stomach (cardiac, pyloric)
____ tuberculum impar
Respiratory System
____ bronchus (primary)
____ epiglottis
____ lung bud
____ pleural cavity
____ septum transversum
(diaphragm)
____ trachea
80
Both
6 mm Pig Embryo (4 of 5)
Extraembryonic…
Embryonic…
Circulatory System
____ aorta (dorsal, descending)
____ aorta (ventral, truncus
arteriosus, conotruncus)
____ aortic arches (1, 2, 3, 4)
____ cardinal veins (anterior,
posterior, common)
____ atrium (auricle)
____ basilar artery*
____ carotid artery (internal)
____ caudal artery
____ celiac artery*
____ conus (bulbus) arteriosus
(bulbus cordis)
____ ductus arteriosus (aortic
end of 6th aortic arch)
____ ductus venosus
____ epimyocardium
____ heart
____ hepatic portal vein
____ interatrial foramen
____ interatrial septum
____ intersegmental artery
____ interventricular septum
____ mesenteric artery,
superior (vitelline artery)
____ myocardium
____ pericardial cavity
____ pulmonary artery (left,
right)
____ sinus venosus
____ trabeculae carnae
____ umbilical (allantoic)
artery*
____ umbilical (allantoic) vein
(right, left)
____ vena cava (inferior)
____ ventricle (cardiac)
81
Both
6 mm Pig Embryo (5 of 5)
Extraembryonic…
Embryonic…
Circulatory System
(continued)
____ vertebral artery
____ vitelline
(omphalomesenteric) vein
Urogenital System
____ genital ridge
____ glomerulus
____ mesonephric (Wolffian)
duct
____ mesonephric tubule
____ mesonephros
____ metanephros
Skeleto-muscular System
____ dermatome
____ hyoid arch
____ limb bud
____ mandibular arch
____ maxillary process
____ myotome
____ notochord
____ sclerotome
____ somite
____ tail
____ visceral arch (1, 2, 3, 4)
____ visceral groove
____ visceral pouch (1, 2, 3, 4)
Endocrine System
____ adenohypophysis
(Rathke’s pocket,
anterior pituitary)
____ hypophysis (pituitary
gland)
____ neurohypophysis
(posterior pituitary,
infundibulum)
____ thyroid diverticulum
82
Both
Laboratory Identification List
Some terms in the lists have an asterisk (*) in front of them. These terms are usually processes, to which you cannot point,
but sometimes they are very small or obscure structures. Each slide set is unique, and not all embryos so labeled are at
exactly the same developmental stage. It is possible that a particular structure is too rudimentary to be identified on your
slides, but you must still know the pertinent information about that structure. Check with your instructor to be certain that
you haven’t simply missed seeing it on your slides. Ideally, one would examine several slide sets of a particular stage of
development. Recall that the first time a term is added to the list, it is italicized, but not subsequently. As you progress to
later stages, you will be able to identify the new terms easily by this style.
Items appear in ITALICS the first time you are asked to consider (processes) or identify structures, but not thereafter.
Notes on identifying central nervous system structures: In this course we differentiate between cavities and tissues of the
central nervous system. The suffix “coel” refers to a cavity, e.g., mesocoel. In such cases, the tip of your pointer must be
in the mesencephalon cavity when making an identification. The suffix “encephalon” refers to tissue, e.g.,
mesencephalon. In such cases, the tip of your pointer must be on mesencephalon tissue when making an identification.
Note that the various cavities and tissues of the developing central nervous system are continuous with one and other.
Thus, when making an identification, you must point to a definitive example of the CNS tissue or cavity you are asked to
identify. “Definitive” means that you must not point to a region where the cavity or tissue is transitioning from one
specific tissue region or cavity to another. When you point at a CNS tissue or cavity you are asked to identify on a lab
exam, your ID must clearly be the specific tissue or cavity that the identification question asks for.
10 mm Pig Embryo (page 1 of 7)
Extraembryonic…
____ allantoic stalk
____ allantois
____ amnion*
____ amniotic cavity*
____ chorion* (serosa)
____ seroamniotic
junction/raphe
____ subcaudal pocket*
____ subcephalic pocket*
Embryonic…
____ flexure (cephalic, cranial,
cervical))
____ flexure (caudal)*
____ head
____ head mesenchyme
____ limb bud
____ tail bud
____ tail fold
____ visceral cleft/groove
(1, 2, 3, 4)
____ visceral pouch (1, 2, 3, 4)
Both
____ allantoic stalk
____ coelom (extraembryonic
coelom = exocoel)
____ ectoderm (non-neural)
____ endoderm
____ epidermis
____ mesoderm
____ somatopleure
____ splanchnopleure
Nervous & Sensory System
(Note: CN = Cranial Nerve)
____ abducens nerve (CN #6)
____ accessory nerve (CN #11)
____ accessory ganglion (next
to CN #11, but really part
of CN #10)
____ acoustic ganglion (CN #8)
____ alar(roof) plate
____ anterior chamber (ocular)
____ auditory nerve (CN #8)
____ auditory (otic) vesicle
____ basal (floor) plate
© S.R. Haley & S.C. Kempf,
____ brachial plexus
7/25/11
83
10 mm Pig Embryo (page 2 of 7)
Extraembryonic…
Embryonic…
Nervous & Sensory System
____ cerebellum (presumptive =
metencephalon)
____ cerebral hemispheres
(presumptive,
=telencephalic vesicles)
____ choroid fissure
____ cornea
____ diencephalon
____ diocoel
____ dorsal isthmus
____ endolymphatic duct
____ependymal layer
____ epiphysis (pineal gland)
____ facial nerve (CN #7)
____ geniculate ganglion(CN
#7)
____ glossopharyngeal nerve
(CN #9)
____ hypoglossal nerve (CN
#12)
____ infundibulum of
diencephalon
(=neurohypophysis,
=pars nervosa)
____ jugular ganglion (CN #10)
____ lens
____ mantle layer
____ marginal layer
____ medulla oblongata
(presumptive, =
myelencephalon)
____ mesencephalon
____ mesocoel (aqueduct of
Sylvius)
____ metacoel
____ metencephalon
____ myelencephalon
____ myelocoel
____ nodose ganglion (CN #10)
____ neural ectoderm
____ oculomotor nerve (CN #3)
____ olfactory bulb
____ olfactory nerve (CN #1)
____ olfactory pit
____ olfactory placode
____ optic cup
84
Both
© S.R. Haley & S.C. Kempf,
7/25/11
10 mm Pig Embryo (page 3 of 7)
Extraembryonic…
Embryonic…
Nervous & Sensory System
____ optic nerve (CN #2)
____ optic stalk
____ optic vesicle
____ petrosal ganglion (CN #9)
____ posterior chamber (ocular)
____ prosocoel
____ retina (pigmented,
sensory)
____ rhombencephalon
____ rhombocoel
____ semilunar (Gasserian)
ganglion (CN #5)
____ spinal cord
____ spinal (dorsal root)
ganglion
____ spinal nerve (dorsal,
ventral roots)
____ *superior ganglion (CN
#9)
____ telencephalon
____ telocoel
____ trigeminal nerve (CN #5)
(mandibular, maxillary,
and ophthalmic
branches)
____ trochlear nerve (CN #4)
____ vagus nerve (CN #10)
85
Both
© S.R. Haley & S.C. Kempf,
7/25/11
10 mm Pig Embryo (page 4 of 7)
Extraembryonic…
Embryonic…
Both
Digestive System
____ appendix
____ caecum
____ cloaca
____ cloacal plate (membrane)
____ colon (large intestine)
____ ductus choledochus
(common bile duct)
____ duodenum
____ esophagus
____ falciform ligament
____ gall bladder
____ glottis
____ hepatic sinusoid
____ hindgut
____ liver diverticulum
____ mesocolon
____ mesoduodenum
____ mesogastrium
____ omental bursa
____ omentum (greater, lesser)
____ pancreas (dorsal, ventral)
____ peritoneal cavity
____ pharynx
____ Seessel’s pocket (pre-oral
gut)
____ small intestine
____ stomach (cardiac, pyloric)
____ tuberculum impar (root of
tongue)
© S.R. Haley & S.C. Kempf,
7/25/11
86
10 mm Pig Embryo (page 5 of 7)
Extraembryonic…
Embryonic…
Both
Respiratory System
____ lung buds (primary bronchi)
____ pleural cavity
____ septum transversum
(diaphragm)
____ trachea
Circulatory System
____ aorta (dorsal, descending)
____ aorta (ventral = truncus
arteriosus, conotruncus)
____ aortic arches (3, 4, 6)
____ atrioventricular valves
____ cardinal veins (anterior,
posterior, common)
____ atrium (auricle)
____ basilar artery*
____ bulbus arteriosus (=conus
arteriosus, =bulbus cordis,
=conotruncus)
____ carotid artery (internal)
____ caudal artery
____ celiac (celiac) artery*
____ conus (bulbus) arteriosus
(bulbus cordis)
____ ductus arteriosus (aortic end
of 6th aortic arch)
____ ductus venosus
____ epimyocardium
____ heart
____ hepatic portal vein
____ iliac artery
____ interatrial foramen
____ interatrial septum
____ segmental artery
____ interventricular septum
____ jugular vein (internal)
____ mesenteric artery, superior
(vitelline artery)
____ mitral valve (left)
____ myocardium
____ pericardial cavity
____ pulmonary artery (left, right)
87
© S.R. Haley & S.C. Kempf,
7/25/11
10 mm Pig Embryo (page 6 of 7)
Extraembryonic…
Embryonic…
Both
Circulatory System
(continued)
____ sinus venosus
____ trabeculae carnae
____ tricuspid valve (right)
____ umbilical (allantoic)
artery*
____ umbilical (allantoic) vein
(right, left)
____ vena cava (inferior;
postcaval vein)
____ ventricle (cardiac)
____ vertebral artery
____ vitelline
(omphalomesenteric) vein
Circulatory System
____ umbilical (allantoic)
artery*
____ umbilical (allantoic) vein
Urogenital System
____ genital ridge
____ genital tubercle*
____ glomerulus
____ mesonephric (Wolffian)
duct
____ mesonephric tubule
____ mesonephros
____ metanephros
____ primordial germ cells*
____ urogenital sinus
Skeleto-muscular System
____ dermatome
____ hyoid arch
____ limb bud
____ mandibular arch
____ maxillary process
____ myocoel
____ myotome
____ notochord
____ sclerotome
____ somite
____ tail
____ visceral arch (1, 2, 3, 4)
____ visceral groove
____ visceral pouch (1, 2, 3, 4)
88
© S.R. Haley & S.C. Kempf,
7/25/11
10 mm Pig Embryo (page 7 of 7)
Extraembryonic…
Embryonic…
Endocrine System
____ adenohypophysis (Rathke’s
pocket, anterior pituitary)
____ hypophysis (pituitary gland)
____ neurohypophysis (posterior
pituitary, infundibulum)
____ thyroid diverticulum
89
Both
© S.R. Haley & S.C.
Kempf,
7/25/11
Lab Handout 14 VERTEBRATE DEVELOPMENT BIOL 4410
Tooth Development
Each slide set is unique, and not all tissues so labeled are at exactly the same developmental stage. It is possible that a
particular structure is too rudimentary to be identified on your slides, but you must still know the pertinent information
about that structure. Check with your TA to be certain that you haven’t simply missed seeing it on your slides. Ideally,
one would examine several slide sets of a particular stage of development.
Adult Tooth
alveolus
alveolar bone
artifact
blood vessels
cementum
crown
dentin
enamel space
gingival
gingival epithelium
junctional epithelium
keratinized layer
lamina propria
marrow cavity
odontoblasts
periodontal ligament
pulp
root
sulcular epithelium
sulcus
Tome’s fibers
vetible
Developing Tooth
alveolar bone
ameloblasts
bell stage
capillaries
dental lamina = dental ledge
dental papilla
dentin
enamal organ
enamel space
head mesenchyme
inner enamel epithelium
labiogingival lamina
maxilla
mandible
nasal cavity
odontoblasts
oral cavity
oral epithelium
outer enamel epithelium
outer sheath
preameloblasts
predentin
pulp
pulp mesenchyme
stellate reticulum
tongue
vestibular lamina
vomeronasal organ
90