GA - Amack - 2/10 - Embryology of the Gut

Question 1

What is meant by retroperitoneal?

Answer 1

Organs that lie behind or outside the peritoneal cavity and are covered only on one surface by a single layer of peritoneum are considered retroperitoneal

Question 2

What is the cause and consequences of duodenal atresia?

Answer 2

Duodenal atresia is the occlusion of the duodenal lumen if canalization fails to occur. Infants with this congenital defect initially exhibit polyhydramnios

Question 3

What is a Meckel’s diverticulum?

Answer 3

Meckel’s diverticulum is a persistent remnant of the vitelline duct. Most cases are asymptomatic, but 1- 3% of individuals develop intestinal obstruction or GI bleeding

Question 4

What is physiological umbilical herniation?

Answer 4

Due to growth of the midgut and other abdominal organs, there is not enough room in the abdominal cavity for the midgut to develop. Thus, the primary intestinal loop herniates into the umbilical cord

Question 5

Describe the difference between omphalocele and gastroschisis

Answer 5

Omphalocele is the extrusion of visceral organs through the umbilical ring that is covered by a thin membrane, whereas gastroschisis is an abdominal wall defect in which bowel protrudes through the abdominal wall (not the umbilical ring) into amniotic cavity and has no covering

Question 6

What is the cause and consequences of volvulus?

Answer 6

Volvulus is the twisting of the intestine back on itself, which can result in intestinal obstruction and compromised blood supply

Question 7

The urorectal septum divides the cloaca into a dorsal __1__ and a ventral __2__

Answer 7

1. anorectal canal

2. urogenital sinus

Question 8

What causes Hirschprung disease?

Answer 8

Hirschsprung disease is caused by the lack of parasympathetic ganglia in the bowel wall. These ganglia are derived from neural crest cells, thus defects in neural crest cell migration can result in Hirschprung disease

Question 9

How does an annular pancreas form?

Answer 9

An annular pancreas results when the two portions of the ventral pancreatic bud migrate in opposite directions around the duodenum. The duodenum surrounded by pancreatic tissue can become constricted or obstructed

Question 10

Describe the two rotations of the midgut

Answer 10

First, the elongating intestine rotates counterclockwise 90o around the superior mesenteric artery while it is in the umbilicus (physiological umbilical herniation).

Second, after the midgut has returned to the abdominal cavity, it undergoes a180o counterclockwise rotation. Altogether, the midgut rotates 270o from its initial position