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Human Development SSN Handout
Dec. 5, 2002
1. Fill In the Blank
Several underlined words in the following paragraph were substituted Freudian Slip style. Please correct them using
the words regarding cell fate during development. (i.e. use words like potency, commitment, etc)
When I left college, I was bewildered – I had a choice of careers. I was receptive to respond to a variety of signals
from my environment, the interaction of which led to my decision to enter medical school. Once I came here, my
fate was sealed, because I was becoming a doctor if no further signals tell me to assume another fate. However, if
properly induced, I can still become an MBA, because I am not yet a slave to my fate.
2. Early Development is marked by the formation of several cavities listed below. Please describe where, how,
and when they are formed
Structure
Blastocyst Cavity
Where
How
When
Primary Yolk Sac (PYS)
Amniotic Cavity
Extraembryonic
Reticulum
Chorionic Cavity
Secondary Yolk Sac
(SYS)
3. Where does the developing embryo hatch out of the zona pellucida?
a. upon fertilization
b. in the ampulla
c. in the distal 1/3 of oviduct
d. during birth
e. in the uterus
4. Link the following molecules on eggs with molecules on sperm with their function:
Egg
ZPGP III
61-integrin
Sperm
Fertilin
Galactosyl transferase
Function
Sperm-egg Attachment
Sperm-egg Fusion
(there’s no # 5!)
6. Upon fertilization, the egg is activated to prevent polyspermy. Which one of the responses listed below is absent
in mammals?
a.
b.
c.
d.
fusion of cortical granules with plasma membrane
Calcium wave across the cell
Hydrolase degradation of O-linked oligosaccharides
Ovoperoxidase crosslinking of tyrosines in the ECM, making it insoluble
7.What happens if the hypoblast is rotated 90 degrees PRIOR to primitive
streak formation?
a) Primitive streak will not form as a certain orientation of the hypoblast
is needed for formation
b) Primitive streak will form normally. Presence of hypoblast determines
formation of primitive streak, while the AVE determines directionality.
c) Primitive streak will form perpendicular to the axis of the hypoblast
d) Primitive streak will form parallel to the axis of the hypoblast
8.Which of the following cells exists throughout the entire life of the
primitive streak?
a) paraxial mesoderm precursors
b) endoderm precursors
c) heart progenitors
d) none of the above
9. The dorsal lip of the blastopore is the amphibian homologue of the
______________ in humans.
10. Which takes place first, cephalocaudal or lateral flexion?
- During cephalocaudal flexion, describe what happens with the heart and
septum transversum.
- During lateral flexion, describe how the gut tube is formed.
11. The primitive pericardial cavity is separated from the peritoneal cavity
by the septum transversum. They remain in continuity through the
______________________.
12. Define intraperitoneal, retroperitoneal, and secondarily retroperitoneal.
Give examples of each.
13. Which of the following statements regarding the development of the nervous system in mammals is correct?
(A)
(B)
(C)
(D)
Neural crest cells arise from ectoderm, and neural crest cells can become motor neurons.
“Neural Induction” actually involves suppression of an epidermal fate by molecules such as BMP-4.
Ancephaly occurs when the posterior neuropore fails to close.
Neurons born within the ventricular zone at earlier stages (oldest neurons) migrate to the deepest layers
of the cortex.
(E)
The birthdays of neurons and glial cells in the CNS can be visualizing using H&E staining with the aid
of immunofluorescence microscopy. The neuron is stained a dark blue after it undergoes its last “S”
phase.
14. Which of the following statements regarding mesoderm formation is false?
(A)
(B)
The most rostral and most caudal somitomeres do not form somites; they form bones.
Treating pregnant mice with retinoic acid during gastrulation will not change the number of somites,
but the resulting in “mice” with have only big butts (posterior ends) and no heads.
(C)
The congenital presence of a hemi-vertebrae on the left or right side can cause scoliosis, but if this
defect occurs in the dorsal-ventral plane, lordosis or kyphosis can occur.
(D)
Lateral mesoderm will give rise to the pericardial lining.
(E)
Somites must upregulate E-cadherin and re-epithelialize to resume mesenchymal phenotype and
migrate to tissues, forming connective tissues.
15. Fill in the blank:
The developing brain is initially divided into the prosencephalon, _________________, and _________________.
Rapid accumulation of fluid creates pressure that causes the rapid enlargement of brain vesicles. Associated with
the C-bending of the embryo, there is the prominent formation of the _________________ flexure in the
_______week followed by the _________________ flexure in the _______week. The prosencephalon is now
further subdivided into the _________________ and a more caudal _________________ with prominent optic
vesicles its later walls. (see 5-6)
16. Fill in the blank:
In the trunk, _________________ proteins are expressed in the _________________section of each
_________________, and neural crest cells avoid are repelled by them. The vagal and
_________________ neural crest cells migrate and form the _________________ nervous system. Failure
to reach their destination will result in this developmental disease, _______________________.
17. Short Answer:
Neural crest cells are crucial for the creation of many critical structures such as the PNS, facial cartilage and adrenal
medulla.
(1) Briefly explain how and from what neural crest cells arise and what signaling molecules are important for their
induction.
(2) What sort of interactions and molecules are important for the migration of neural crest cells to their targets? (23 sentences)
18. If you could peer into the trunk (T1) of a developing embryo and could visualize an individual somite, explain
what you would see. What structures would arise from this somite. You needn’t explain things that I can’t see—
such as what genes are in play or signaling molecules.
19.
I.
II.
III.
IV.
V.
The somatopleuric membrane gives rise to the muscle and fibrous tissue of the bowel.
The lesser sac (or omental bursa) arises as a consequence of the rotation and movement of the stomach
during development.
Most of the pancreas, including the main pancreatic duct (of Wirsung), is derived from the dorsal
pancreatic bud.
The duodenum is a retroperitoneal structure.
The urorectal septum is formed by four folds, the superior and inferior folds of Tourneux and the two
lateral folds of Rathke.
Which of the above statements is/are true?
A. I only
B. II only
C. II and III
D. IV and V
E. I, II, III, and V
20. Fill-in-the-blank question
Rotation of the midgut:
Initially, the gut communicates with the yolk sac via the
, which is at the leading edge of a Ushaped loop of gut formed by the rapidly growing bowel. By the early sixth week, this loop of gut (the primarly
intestinal loop) herniates into the
. As this occurs, the primary intestinal loop rotates around the axis
of the
artery by
degrees
wise (looking at the embryo’s ventral surface). Reduction of the
midgut hernia occurs during the tenth week, during which the primary intestinal loop rotates
degrees
wise.
21. The following conditions can occur as a result of abnormalities in gut development. Please provide a brief
description of each:
A. Polyhydramnios
B. Volvulus
C. Omphalocele
D. Umbilical hernia
E. Meckel’s diverticulum
22. Multiple choice question
I.
The expression of MUC-1 is downregulated by progesterone.
II.
To avoid immunological rejection, the hypoblast expresses a special form of antigen that masks its identity
III.
During formation of the placenta, the embryonic trophoblast invades beyond the upper myometrium.
IV.
Decidual cells promote cytotrophoblast invasiveness by secreting hepatocyte growth factor.
V.
At six months, significant components of the barrier between maternal and fetal blood include:
syncytiotrophoblast, cytotrophoblast, and endothelium of the fetal capillary.
Which of the above statements is/are true?
A. I and II
B. III only
C. IV only
D. III and IV
E. II, III, and IV
23. Fill-in-the-blank question
Hormonal regulation of the menstrual cycle:
On day zero of the 28 day cycle, the
begins to slough. By day five,
from the
brain stimulates the pituitary to release
and
. These hormones promote the
development of
, which secrete
; this, in turn, promotes rebuilding of the glands and
blood vessels of the
. Following release of the ovum (day 14), the corpus luteum secretes high levels
of
, which causes endometrial glands to become secretory. Maintenance of the corpus luteum depends
on
. However,
secretion depends upon
secretion, which is inhibited by
steroid hormones secreted by the corpus luteum. Unless there is a fertilized ovum, the corpus luteum will
degenerate and the
will break down. If there is a fertilized ovum, cells of the
synthesize
, rescuing the corpus luteum.
24. Short answer question
Please describe the following problems that can occur during pregnancy:
A. Tubal pregnancy
B. Placenta praevia
C. Preeclampsia
25. Which of the following statements is correct?
A. During angiogenesis, large vessels extend out and branch to form smaller vessels and capillary beds
B. Vitelline veins remove waste from the embryo
C. Hemangioblasts are the precursors for blood cells and endothelial cells
D. Splanchnic mesodermal cells clump to form blood islands, which develop into blood vessels in the embryo
26-33: Choose the precursor that gives rise to the structure (choices may be used 0, 1, or more times)
A. Bulbus cordis
B. Right sinus horn
C. Septum intermedium
D. Endocardial cushions
E. Septum primum
F. None of the above
26. ____ Infundibulum
27. ____ Muscular portion of the interventricular septum
28. ____ Sinoatrial node
29. ____ R atrium, smooth portion (sinus venarum)
30. ____ Foramen ovale
31. ____ Pulmonary trunk
32. ____ R ventricle, trabeculated portion
33. ____ Membranous portion of the interventricular septum
34. Which choice correctly describes the order in which blood flows through a 4th week embryo?
A: tissue -> vitelline veins -> umbilical veins -> placenta
B. posterior cardinal veins -> sinus horns -> primitive atrium -> atrioventricular canal (AV canal) -> L
ventricle -> R ventricle -> aortic arches -> umbilical arteries
C. sinus venosus -> R atrium -> R ventricle -> L ventricle -> 4th aortic arches -> dorsal aortae -> tissue
D. vitelline veins -> sinus horns -> sinoatrial orifice -> L ventricle -> dorsal aortae
35. Which of the following correctly describes the order in which the bulk of blood flows, from the given origin
(first listed location in each choice), in a fully-developed fetus?
A. Lower limbs -> IVC -> R Atrium -> L Atrium -> L Ventricle -> Aorta
B. SVC -> R ventricle -> ductus arteriosus -> lungs
C. Umbilical vein -> liver sinusoids -> IVC -> RA
D. Pulmonary artery -> lungs -> pulmonary vein -> L Atrium
36-39. Match the defect to the developmental event (choices may be used 0, 1, or more times)
A. Septum primum resorption
B. Looping of the heart
C. Conotruncal septum formation
D. None of the above
36. Persistent truncus arteriosus
37. Dextrocardia
38. Ostium secundum defect (ASD)
39. Tetralogy of Fallot (TOF)