Young's Embryology MCQs Flashcards
1
Q
- Anorectal agenesis is more common in males than females and is usually associated with a rectourethral fistula. The embryological basis of the fistula is
A. abnormal partitioning of the cloaca B. agenesis of the urorectal septum C. failure of fixation of the hindgut D. failure of the proctodeum to develop E. premature rupture of the anal membrane
A
A
2
Q
- The junction of the endodermal epithelium of the hindgut and the ectoderm of the proctodeum or anal pit is believed to be indicated by the
A. external sphincter B. levator ani muscles C. pectinate line D. superior ends of the anal columns E white line
A
C
3
Q
- Massive rectal bleeding was observed in an infant. The color of the blood ranged from bright to dark red. The child appeared to be free of any pain. A diagnosis of Meckel’s diverticulum was made. This condition is associated with which of the following?
A. Duplication of the intestine. B. Herniation of the intestines. C. Remnant of the yolk stalk. D. Nonrotation of the midgut. E. Subhepatic cecum and appendix.
A
C
4
Q
- As the stomach acquires its adult shape, it rotates around its longitudinal axis. Which of the following events does not result from this rotation?
A. The ventral border of the stomach moves to the right.
B. The dorsal border of the stomach moves to the left.
C. The dorsal mesogastrium is carried to the left.
D. The duodenum rotates to the right.
E. The dorsal part of the stomach grows rapidly.
A
E
5
Q
- Which of the following is the most common type of anorectal malformation?
A. Anal agenesis B. Anorectal agenesis C. Anal stenosis D. Ectopic anus E. Persistant anal membrane
A
B
6
Q
- The anal membrane usually ruptures at the end of the week.
A. 5th B. 6th C. 7th D. 8th E. 9th
A
C
7
Q
- Pyloric stenosis is characterized by vomiting, usually starting in the second or third week after birth, which becomes increasingly projectile. The narrowing of the pyloric lumen results primarily from:
A. a diaphragm-like narrowing of the pyloric lumen
B. a so-called “fetal vascular accident” in the pylorus
C. hypertrophy of the circular muscle layer
D. hypertrophy of the longitudinal muscle layer
E. persistence of the solid stage of pyloric development
A
C
8
Q
- When the primary intestinal loop undergoes rotation between weeks 6 and 11, which of the following blood vessels lies along the axis around which it rotates ?
A. abdominal aorta B. celiac artery C. inferior mesenteric artery D. left umbilical vein E. superior mesenteric artery
A
E
9
Q
- In a baby born with reversed rotation of the midgut, the duodenum lies ventral to the transverse colon. In the embryogenesis of this malformation, the primary intestinal loop (viewed from in front) accomplishes a net rotation around its long axis of how many degrees and in which direction?
A. 90 degrees clockwise B. 90 degrees counterclockwise C. 180 degrees clockwise D. 270 degrees counterclockwise E. 270 degrees clockwise
A
A
10
Q
- An infant is born with a mid-ventral defect of the abdominal wall of the type that is often attributed to a failure of the umbilical ring to close. The viscera that protrude through this defect are covered with amniotic membrane alone. A term for this infant’s malformation is
A. cloacal exstrophy B. epispadias C. gastroschisis D. meningocele E. omphalocele
A
E
11
Q
- An infant is born with an abdominal wall defect that is located just to the right of the umbilicus. The protruding viscera is covered by neither amniotic membrane nor parietal peritoneum. A term for this infant’s malformation is
A. epispadias B. gastroschisis C. omphalocele D. omphalomesenteric fistula E. urachal fistula
A
B
12
Q
- Delay in passage of meconium was noted in a male infant. Additional symptoms included constipation, vomiting, and abdominal distention. A barium enema and x-rays revealed a distended sigmoid colon and a nonperistaltic rectum. Pathology reported a normal number of parasympathetic ganglion cells in the sigmoid colon. A diagnosis of congenital megacolon (Hirschsprung’s disease) was made. This condition is associated with which of the following?
A. failure of the endodermal cells to line the colonic cavity
B. failure of neural crest cells to migrate forming the enteric parasympathetic ganglia
C. failure to recanalize the intestine
D. hypertrophy of myoblasts forming the inner circular layer of smooth muscle
E. hypertrophy of myoblasts forming the outer longitudinal layer of smooth muscle
A
B
13
Q
- An infant is born with a defect in the umbilicus that exposes intestinal mucosa and oozes meconium. A term for this infant’s malformation is
A. gastroschisis B. meningocele C. omphalocele D. omphalomesenteric fistula E. urachal fistula
A
D
14
Q
- The teeth of an 8-year-old child were badly discolored, giving them a brownish yellow appearance, and the enamel was hypoplastic. This condition is usually associated with which of the following?
A. congenital syphilis E. diazepam D. herpes simplex virus C. phenytoin B. tetracyclines
A
B
15
Q
- In humans, cleft lip, with or without cleft palate, usually results from
A. cortisone B. infectious disease C. radiation D. rubella virus E. trimethadione
A
E
Trimethadione is an oxazolidinedione anticonvulsant. It is most commonly used to treat epileptic conditions that are resistant to other treatments.
