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Introduction
- What is embryogenesis? When does it occur in humans?
- What is morphogenesis? When does it occur in humans?
- Elaborate on the phrase “ontogeny recapitulates phylogeny”. Who termed this phrase, and
what prompted him to say it? What are some ways in which it is true? What are some ways in
which it is false? (Bonus: revisit this question once we cover the chapter about comparative
embryology and elaborate on your answer!)
For each of the following processes, give a brief definition. As the class progresses, we will
encounter examples of each. Revisit this question to list examples as we encounter them!
Epiboly
- definition:
- examples:
Invagination
- definition:
- examples:
Evagination
- definition:
- examples:
Involution
- definition:
- examples:
Ingression
- definition:
- examples:
Delamination
- definition:
- examples:
Gametogenesis
- Compare and contrast mitosis and meiosis.
- Define ploidy:
- Define n-number:
- Compare and contrast spermatogenesis and oogenesis.
Label all stages of gametogenesis below. Indicate ploidy and n-number at each stage.
Male
- Where are the primordial germ cells located in the testis? Be as specific as possible.
- What are the support cells in spermatogenesis? What is their function?
- Describe the relationships between spermatogonia and Type Ap, Type Ad, and Type B
primordial germ cells.
Label each region and structure of the mature sperm cell in the following image, and describe
each region or structure’s function.
Label all cells in the following image, and indicate each germ cell’s ploidy and n-number, as
well as all meiotic and/or mitotic divisions.
Female
Titleeachstageofoocytedevelopmentinthe
imagetotheright.Indicatetheploidyandnnumberofthegermcellineachstage.Also
labeleverythingthatcanbelabeledineach
stage.
-Describetheprocessofovulation.
-Whendoesthefirstmeioticdivisionoccurin
females?
-Whendoesthesecondmeioticdivisionoccur
infemales?
-Whatisapolarbody?
-Whatisthestructureandfunctionofthe
zonapellucida?
-Whatisthestructureandfunctionofthe
cumulusoophorus?
-Whatisthestructureandfunctionofthe
coronaradiata?
-Defineyolk:
-Usefancyyolkwordstodescribethehuman
yolkdistributionandclassification.
Fertilization
- What are some problems with fertilization? How do humans deal with each of these
problems? Why is fertilization worth going through all of those bad things?
List the 5 big steps of fertilization, and describe all sub-parts of each in the following chart.
Big step
Sub-parts
Description
- List all enzymes involved in fertilization, and indicate what structure/layer each enzyme
breaks down.
- Compare and contrast the “Fast block” and “Slow block” oocyte responses. Why are these so
important?
Early Development
Fill in the blanks:
Fusion of the male and female pronuclei creates a _______________, which undergoes
____________ to create two cells called __________________. These cells continue dividing via
MITOSIS / MEIOSIS (circle one), eventually becoming a ____________ when it reaches 12 cells.
A fluid-filled cavity forms, at which point the ball of cells is called a _________________. The
outer cell mass is called the __________________ and the inner cell mass is called the
________________. Every part of an adult arises from the INNER / OUTER (circle one) cell mass.
Complete the following flow chart, drawing arrows from each word down to the structures in
the next row that it will become. When applicable, indicate the process by which this
transformation occurs. Think of more structures that we’ve learned so far that arise from
ectoderm, mesoderm, and endoderm, and add these structures to the final row.
Blastocyst
Embryoblast
Epiblast
Hypoblast
Ectoderm
Neural tube
Neural crest
Trophoblast
Cytotrophoblast
Mesoderm
Placodal ring
Syncytiotrophoblast
Endoderm
Notochord
Somites
Allantois
Essay: Describe the process of gastrulation, using simple labeled diagrams and bullet points.
Time yourself – this should take about 5 minutes.
Essay: Describe the process of notochord formation, using simple labeled diagrams and
bullet points. Time yourself – this should take about 10 minutes.
Essay: Describe the process of neurulation, using simple labeled diagrams and bullet points.
Time yourself – this should take about 5 minutes.
Essay: Describe the process of intraembryonic coelom formation, using simple labeled
diagrams and bullet points. Time yourself – this should take about 5 minutes.
What are the “Big Three” processes that occur during the third week?
What is the relationship between the prechordal plate and oropharyngeal membrane? What
is the significance of these structures? Describe their role during gastrulation and notochord
formation. Which germ layer is missing in this region? What does the oropharyngeal
membrane become in an adult?
Define splanchnopleure:
Define somatopleure:
Describe the formation of the primary and secondary yolk sacs.
Describe the formation of somites from paraxial mesoderm.
In each of the following diagrams, color ectoderm blue, mesoderm red, and endoderm yellow.
Label everything that you can.
Label the following diagrams, color the three germ layers as you did above, and use bullet
points to describe how the tri-laminar embryo folds to become more tube-shaped.