Chapter Questions Flashcards
1
Q
“Which of the following molecules plays an important
role in the determination of the dorsoventral axis of the
developing limb? A. Msx-1
B. Wnt-7a
C. Hoxd-13
D. Pax-1
E. FGF-8”
A
B. Wnt-7a
2
Q
“What molecule is associated with myogenic cells
migrating into the limb bud from the somites?
A. shh
B. BMP-7
C. FGF-4
D. Pax-3
E. En-1”
A
D. Pax-3
3
Q
“What is the principal function of the AER?
A. Stimulating outgrowth of the limb bud
B. Setting up the anteroposterior axis of the limb bud
C. Determining the specific characteristics of the ectodermal
appendages of the limb
D. Determining the pattern of neural ingrowth into the limb
E. Attracting the subcutaneous plexus of capillaries in the
limb bud”
A
A. Stimulating outgrowth of the limb bud
4
Q
"In the developing limb the sonic hedgehog (shh) gene product is produced in the: A. Progress zone B. Region of interdigital cell death C. ZPA D. AER E. Common muscle mass"
A
C. ZPA
5
Q
"The connective tissue of the limb arises from the: A. Paraxial mesoderm B. Neural crest C. Intermediate mesoderm D. Somitic mesoderm E. Lateral mesoderm"
A
E. Lateral mesoderm
6
Q
“6. The formation of clubfoot (talipes equinovarus) is
associated with:
A. A misplaced ZPA
B. Defective cellular migration from somites
C. Thalidomide
D. Oligohydramnios
E. A neural crest defect”
A
D. Ogliohydramnios
7
Q
“An infant whose mother underwent chorionic villus
sampling during pregnancy was born with the tips of
two digits missing. What is a possible cause?”
A
“A tear of the amnion during the chorionic villus sampling
procedure could have resulted in an amniotic band
wrapping around the digits and strangulating their blood
supply, thereby causing the tips to degenerate and fall
off.”
8
Q
“A woman who underwent amniocentesis during
pregnancy gave birth to a child with a duplicated thumb.
What is a possible cause?”
A
“This defect is unlikely to be related to the amniocentesis
procedure because the morphology of the digits is well
established by the time such a procedure is undertaken
(usually around 15 to 16 weeks). The most likely cause is
a genetic mutation.”
9
Q
“If the somites close to a limb-forming region are
experimentally removed, the limbs form without
muscles. Why?”
A
Muscle-forming cells arise from the somites.
10
Q
“10. A child is born with webbed fingers (syndactyly).
What is the reason for this anomaly?”
A
“The immediate cause is likely the absence of programmed
cell death in the interdigital mesoderm. The cause of the
disturbance in cell death is currently not understood.”
11
Q
“1. Which of these cell and tissue types arises from
cranial, but not trunk, neural crest cells?
A. Sensory ganglia
B. Adrenal medulla
C. Melanocytes
D. Schwann cells
E. None of the above”
A
E. None of the above
12
Q
"2. Which molecule is a poor substrate for migrating neural crest cells? A. Laminin B. Chondroitin sulfate C. Fibronectin D. Type IV collagen E. Hyaluronic acid"
A
B. Chondroitin sulfate
13
Q
"3. Neural crest cells arise from the: A. Somite B. Dorsal non-neural ectoderm C. Neural tube D. Splanchnic mesoderm E. Yolk sac endoderm"
A
C. Neural tube
14
Q
“4. A 6-month-old infant exhibits multiple congenital
defects, including a cleft palate, deafness, ocular
hypertelorism, and a white forelock but otherwise dark
hair on his head. The probable diagnosis is:
A. CHARGE association
B. von Recklinghausen’s disease
C. Hirschsprung’s disease
D. Waardenburg’s syndrome
E. None of the above”
A
D. Waardenburg’s Syndrome
15
Q
"5. What molecule is involved in the migration of neural crest cells from the neural tube? A. Slug B. BMP-2 C. Mash 1 D. Norepinephrine E. Glial growth factor"
A
A. Slug
16
Q
"6. Which is not a derivative of the neural crest? A. Sensory neurons B. Motoneurons C. Schwann cells D. Adrenal medulla E. Dental papilla"
A
B.Motoneuron
17
Q
"7. What maintains the competence of neural crest cells to differentiate into autonomic neurons? A. Sonic hedgehog B. Acetylcholine C. Mash 1 D. Glial growth factor E. Transforming growth factor-β"
A
C. Mash 1
18
Q
"8. If trunk neural crest cells are transplanted into the cranial region, they can form all of the following types of cells except: A. Pigment cells B. Schwann cells C. Sensory neurons D. Cartilage E. Autonomic neurons"
A
D. Cartilage
19
Q
“9. How does the segmental distribution of the spinal
ganglia occur?”
A
“Along the length of the spinal cord, migrating neural
crest cells are funneled into the anterior sclerotomal
region of the somites and are excluded from the
posterior half. This results in the formation of a pair of
ganglia for each vertebral segment and space between
ganglia in the craniocaudal direction.”
20
Q
“10. What are three major differences between cranial
and trunk neural crests?”
A
“Cranial crest cells can form skeletal elements; trunk crest
cells cannot. Migrating cranial neural crest cells have
more morphogenetic information encoded in them than
trunk crest cells do. (For example, craniocaudal levels are
specified in cranial crest, whereas they are not fixed in
trunk crest cells.) Cranial crest cells form large amounts
of dermis and other connective tissues, whereas trunk
crest cells do not.”
21
Q
"1. Neural crest–derived cells constitute a significant component of which tissue of the eye? A. Neural retina B. Lens C. Optic nerve D. Cornea E. None of the above"
A
D. Cornea
22
Q
"2. The otic placode arises through an inductive message given off by the: A. Telencephalon B. Rhombencephalon C. Infundibulum D. Diencephalon E. Mesencephalon"
A
B. Rhombencephalon
23
Q
"3. What molecule plays a role in guidance of advancing retinal axons through the optic nerve? A. Pax-2 B. FGF-3 C. BMP-4 D. Pax-6 E. BMP-7"
A
A. Pax-2
24
Q
“4. Surface ectoderm is induced to become corneal
epithelium by an inductive event originating in the:
A. Optic cup
B. Chordamesoderm
C. Optic vesicle
D. Lens vesicle
E. Neural retina”
A
D. Lens vesicle
25
```
"5. The second pharyngeal arch contributes to the:
A. Cochlea and earlobe
B. Auditory tube and incus
C. Stapes and earlobe
D. Auditory tube and stapes
E. Otic vesicle and stapes"
```
C. Stapes and earlobe
26
"6. During a routine physical examination, an infant was
found to have a small segment missing from the lower
part of one iris. What is the diagnosis, what is the basis
for the condition, and why may the infant be sensitive
to bright light?"
"Coloboma of the iris is caused by failure of the choroid
fissure to close during the sixth week of pregnancy.
Because the area of the defect remains open when the
rest of the iris constricts in bright light, excessive
unwanted light can enter the eye through the defect."
27
"7. Why does a person sometimes get a runny nose
| while crying?"
"Some of the secretions of the lacrimal glands enter the
nasolacrimal ducts, which carry the lacrimal fluid into the
nasal cavity."
28
"8. What extracellular matrix molecule is often
associated with migrations of mesenchymal cells, and
where does such an event occur in the developing eye?"
"Hyaluronic acid. Migration of neural crest cells into the
developing cornea occurs during a period when large
amounts of hyaluronic acid have been secreted into the
primary corneal stroma."
29
"9. Why is the hearing of a newborn often not as acute
| as it is a few months later?"
"During the fetal period, the middle ear cavity is filled with
a loose connective tissue that dampens the action of the
middle ear ossicles. After birth, the connective tissue is
resorbed."
30
"10. Why are malformations or hypoplasia of the lower
jaw commonly associated with abnormalities in the
shape or position of the ears?"
"Similar to the lower jaw, much of the external ear arises
from tissue of the first arch bordering the first pharyngeal
cleft."
31
```
"1. The facial nerve (cranial nerve VII) supplies muscles
derived from which pharyngeal arch?
A. First
B. Second
C. Third
D. Fourth
E. Sixth"
```
B. Second
32
```
"2. Cleft lip results from lack of fusion of the:
A. Nasomedial and nasolateral processes
B. Nasomedial and maxillary processes
C. Nasolateral and maxillary processes
D. Nasolateral and mandibular processes
E. Nasomedial and mandibular processes"
```
B.Nasomedial and maxillary processes
33
"3. In cases of holoprosencephaly, defects of facial
structures are typically secondary to defects of the:
A. Pharynx
B. Oral cavity
C. Forebrain
D. Eyes
E. Hindbrain"
C. Forebrain
34
```
"4. Meckel’s cartilage is a prominent structure in the
early formation of the:
A. Upper jaw
B. Hard palate
C. Nasal septum
D. Soft palate
E. Lower jaw"
```
E. Lower jaw
35
"5. An early induction in tooth development consists
of the ectoderm of the dental epithelium acting on
the underlying neural crest mesenchyme. Which of the
following molecules is an important mediator of the
inductive stimulus? A. BMP-4
B. Tenascin
C. Hoxb-13
D. Msx-1
E. Syndecan"
A. BMP-4
36
"6. A 15-year-old boy with mild acne developed a tender
boil along the anterior border of the sternocleidomastoid
muscle. What embryological condition would be included
in a differential diagnosis?"
"One option is simply acne. Another more significant
possibility is a branchial cyst. Branchial cysts are
typically located along the anterior border of the
sternocleidomastoid muscle. One possible reason for
its late manifestation is that the same conditions that
resulted in the boy’s acne caused a simultaneous reaction
in the epidermis lining the cyst."
37
"7. The physician of the 15-year-old boy described in
the previous question determined that the boy had a
congenital cyst that needed to be removed surgically.
What should the surgeon consider during removal of
the cyst?"
"First, all epithelium lining the cyst must be removed,
or the remnants could reform into a new cyst, and the
symptoms could recur. The surgeon also must determine
that the cyst is isolated and not connected to the
pharynx via a sinus, which would result from an
accompanying persistence of the corresponding
pharyngeal pouch."
38
"9. A woman who took an anticonvulsant drug during
the tenth week of pregnancy gave birth to an infant
with bilateral cleft lip and cleft palate. She sued the
physician, blaming the facial malformations on the
drug, and you are called in as an expert witness for
the defense. What would be the basis for your case?"
"By 10 weeks, all the processes of fusion of facial
primordia have already been completed. The cause of the
defects could almost certainly be attributed to something
that influenced the embryo long before the time when
the anticonvulsant therapy was initiated, probably before
the seventh week of pregnancy."
39
"10. A woman who averaged three mixed drinks a day
during pregnancy gave birth to an infant who was
mildly retarded and who had a small notch in an
upturned upper lip and a reduced olfactory sensitivity.
What is the basis for this constellation of defects?"
"These defects could be a manifestation of fetal alcohol
syndrome. They could represent a mild form of
holoprosencephaly, which in this case would relate to
defective formation of the forebrain (prosencephalon).
The defects in olfaction and in the structure of the upper
lip could be secondary effects of a primary defect in early
formation of the prosencephalon."
40
```
"1. Which condition is most closely associated with a
disturbance of neural crest?
A. Anal atresia
B. Meckel’s diverticulum
C. Omphalocele
D. Volvulus
E. Aganglionic megacolon"
```
E. Aganglionic megacolon
41
```
"2. Meckel’s diverticulum is most commonly located in
the:
A. Ileum
B. Ascending colon
C. Jejunum
D. Transverse colon
E. Duodenum"
```
A. Ileum
42
```
"3. The primordium of which structure is located in the
septum transversum?
A. Dorsal pancreas
B. Lung
C. Liver
D. Thymus
E. Spleen"
```
C. Liver
43
```
"4. The yolk stalk is most closely associated with which
artery?
A. Celiac
B. Umbilical
C. Superior mesenteric
D. Aorta
E. Inferior mesenteric"
```
C. Superior mesenteric
44
"5. The dorsal pancreatic bud is initially induced from
the gut endoderm by the:
A. Liver
B. Notochord C. Lung bud
D. Yolk sac
E. None of the above"
B. Notochord
45
```
"6. Splanchnic mesoderm acts as an inducer of all of the
following tissues or organs except:
A. Teeth
B. Trachea
C. Liver
D. Lungs
E. Pancreas"
```
A. Teeth
46
"7. During the first feeding, a newborn begins to choke.
What congenital anomalies should be included in the
differential diagnosis?"
"Esophageal atresia or a tracheoesophageal fistula. In the
former, the milk fills the blind esophageal pouch and
then spills into the trachea via the laryngeal opening. In
the latter, milk may pass directly from the esophagus into
the trachea depending on the type of fistula."
47
"8. A newborn took the first feeding of milk without
incident, but an hour later was crying in pain and
vomited the milk with considerable force. Examination
revealed a hard mass near the midline in the upper
region of the abdomen. What was the diagnosis?"
"Congenital pyloric stenosis. Projectile vomiting is a common
symptom of this condition, and palpation of the knotted
pyloric opening of the stomach confirmed the diagnosis."
48
"9. An infant was noted to extrude a small amount
of mucus and fluid from the umbilicus when crying
or straining. This should make the physician think of
what congenital anomaly in the differential diagnosis?"
"The most likely diagnosis is a vitelline duct fistula
connecting the midgut with the umbilicus. This allows
some contents of the small intestine to escape through
the umbilicus. Another possibility is a urachal fistula (see
Chapter 16), which connects the urinary bladder to the
umbilicus through a persistent allantoic duct. In this case,
however, the escaping fluid would be urine and would
likely not be accompanied by mucus."
49
"10. A newborn was given a cursory physical examination
and was taken home by the mother 1 day after delivery.
Several days later, the mother brought the infant to the
clinic. The infant was in obvious severe discomfort with
a swollen abdomen. Physical examination revealed that
an important congenital anomaly had been overlooked
at the original examination. What was that anomaly?"
"Imperforate anus. When examining a newborn, clinicians
| must ensure that there is an anal opening."
50
"1. Which of the following does not connect directly
with the primary nephric (mesonephric) duct?
A. Metanephros
B. Cloaca
C. Nephrotomes
D. Mesonephric tubules
E. Ureteric bud"
A. Metanephros
51
"2. Which association is correct?
A. Potter’s facies and hydramnios
B. Urachal fistula and hydramnios
C. Horseshoe kidney and superior mesenteric artery
D. GDNF and metanephrogenic blastema
E. Bilateral renal agenesis and compensatory hypertrophy"
D. GDNF and metanephrogenic blastema
52
```
"3. Which defect is strongly associated with
oligohydramnios?
A. Pelvic kidney
B. Renal agenesis
C. Horseshoe kidney
D. Crossed ectopia
E. Polycystic kidney"
```
B. Renal agenesis
53
```
"4. Which anomaly is most closely associated with
exstrophy of the bladder?
A. Epispadias
B. Renal agenesis
C. Anal atresia
D. Pelvic kidney
E. Ectopic ureteral orifice"
```
A. Epispadias
54
```
"5. The uterus arises from the:
A. Paramesonephric ducts
B. Urogenital sinus
C. Mesonephric tubules
D. Pronephric ducts
E. Mesonephric ducts"
```
A. Paramesonephric ducts
55
"6. The floor of the penile urethra in the male is
homologous to what structure in the female?
A. Clitoris
B. Trigone of the bladder
C. Labia majora
D. Labia minora
E. Perineum"
D. Labia minora
56
```
"7. The metanephrogenic blastema is induced by the:
A. Pronephric duct
B. Ureteric bud
C. Mesonephric tubules
D. Allantois
E. Mesonephric duct"
```
B. Ureteric bud
57
"8. Drops of a yellowish fluid were observed around the
umbilicus of a young infant. What is a likely diagnosis,
and what is the embryological basis?"
"The most likely cause is a urachal fistula connecting the
urinary bladder to the umbilicus and allowing the leakage
of urine. This is caused by the persistence of the lumen in
the distal part of the allantois."
58
"9. A woman who gained relatively little weight during
pregnancy gives birth to an infant with large, low-set
ears, a flattened nose, and a wide interpupillary space.
Within hours after birth, the infant is obviously in great
distress and dies after 2 days. What is the diagnosis?"
"Bilateral renal agenesis. The first clue was the mother’s
low weight gain, which could have been the result of
oligohydramnios (although this is not the only cause
for low weight gain during pregnancy). The infant’s
appearance showed many of the characteristics of
Potter’s syndrome, which is caused by intrauterine
pressures on the fetus when the amount of amniotic
fluid is very low."
59
"10. A seemingly normal woman experiences pelvic pain
during the later stages of pregnancy. An ultrasound
examination reveals that she has a bicornuate uterus.
What is the embryological basis for this condition?"
"In normal development, the caudal ends of the
paramesonephric ducts swing toward the midline and
fuse. In this patient’s case, the point of fusion probably
occurred more caudally than normal. This condition
is compatible with a normal pregnancy and delivery,
although in some cases, pain or problems with delivery
can occur."
60
```
"1. Nucleated erythrocytes found circulating in the
embryo are produced in the:
A. Yolk sac
B. Para-aortic clusters
C. Liver
D. Bone marrow
E. None of the above"
```
A. Yolk sac
61
"2. In a 7-month fetus, blood draining the left
temporalis muscle enters the heart via the:
A. Left anterior cardinal vein
B. Coronary sinus
C. Left common cardinal vein
D. Superior vena cava
E. None of the above"
D. Superior vena cava
62
"3. Adherons are inductive particles released by what
structure in the endocardial cushion area?
A. Endocardium
B. Cardiac jelly
C. Myocardium
D. Epicardium
E. None of the above"
C. Myocardium
63
```
"4. Neural crest contributes to the structure of which of
the following?
A. Truncus arteriosus
B. Ascending aorta
C. Pulmonary trunk
D. All of the above
E. None of the above"
```
D. All of the above
64
"5. For which of these cardiovascular malformations is a
patent ductus arteriosus necessary for survival of the
individual?
A. Atrial septal defect
B. Ventricular septal defect
C. Double aortic arch
D. Right subclavian artery from arch of aorta
E. None of the above"
E. None of the above
65
"6. Five days after birth, an infant becomes cyanotic
during a prolonged crying spell. The cyanosis is most
likely caused by venous blood entering the systemic
circulation through the:
A. Interatrial septum
B. Ductus arteriosus
C. Ductus venosus
D. Umbilical vein
E. Interventricular septum"
A. Interartrial septum
66
```
"7. The internal carotid artery arises from aortic arch
number:
A. 1
B. 2
C. 3
D. 4
E. 5"
```
C. 3
67
"8. A 12-year-old boy tells his physician that over the
past few months he has noticed some difficulty in
swallowing when eating meat. The physician performs a
physical examination and orders an upper
gastrointestinal x-ray series. After examining the films,
the physician refers the boy for some vascular studies.
What is the reasoning behind this decision?"
"The physician suspected that the boy had a double aortic
arch or a right aortic arch, either of which can cause
difficulty in swallowing (dysphagia) during childhood,
especially when growth spurts are occurring. Another
possibility for an embryologically based dysphagia is
esophageal stenosis."
68
"9. An individual with atresia of the mitral valve could
not survive after birth without other defects of the
cardiovascular system that could compensate for the
primary defect, in this case a complete blockage
between the left atrium and ventricle. Construct at least
one set of associated defects that could physiologically
compensate for the disruption caused by the mitral
atresia."
"To survive, an individual with this defect would have to
have a means for draining blood entering the left atrium
and a means of transporting blood into the left ventricle
or the systemic circulation. One combination that would
compensate is an atrial septal defect, which allows
incoming blood to escape from the left atrium, and an
associated ventricular septal defect, which allows blood
from the right ventricle to pass into the left ventricle.
A patent ductus arteriosus added to the first two
compensatory defects could also help to balance the
circulation by adding blood to the systemic side of
the circulation. This would not be very helpful in the
physiological sense, however, because the added blood
would be unoxygenated blood entering the aorta from
the pulmonary artery."
69
"10. What is the embryological basis for a duplication of
| the inferior vena cava caudal to the kidneys?"
"Persistence of the caudal segment of the left
supracardinal vein. Normally, the caudal segment
of the right supracardinal vein persists and becomes
incorporated into the inferior vena cava, and the
corresponding segment of the left supracardinal vein
disappears (see Fig. 17.12). A wide variety of anomalous
patterns of the abdominal veins exist."
