Embryology

Question 1

what does the endoderm form in the GIT

Answer 1

epithelium of mucosa, associated ducts and glands

Question 2

what does the visceral mesoderm form in the GIT

Answer 2

lamina propria, muscularis mucosa and muscularis externa

Question 3

why is rotation important

Answer 3

Rotation of different parts of the gut bring the mesenteries into their final positions

Question 4

what forms the ventral mesentery

Answer 4

Lesser omentum and falciform ligament form from the ventral mesentery

Question 5

what forms the greater omentum

Answer 5

Continued growth of the dorsal mesentery forms the greater omentum

Question 6

what does the growth and rotation of the stomach creat

Answer 6

the lesser sac and causes the dorsal mesentery to bulge

Question 7

what is the caudal portion of the foregut

Answer 7

parts 1 and 2 of the duodenum

Question 8

what is the cranial portion of the midgut

Answer 8

parts 3 and 4 of the duodenum

Question 9

what germ layer forms the liver and lining of biliary tree

Answer 9

endoderm

Question 10

what germ layer is the spleen derived from

Answer 10

mesoderm- not gut tube

Question 11

what does the mid gut communicate with or most of its development

Answer 11

the yolk sac

Question 12

what is herniation of the midgut

Answer 12

the intestine elongates and moves outside of the embryonic abdomen herniating into the base of the umbilical cord. This occurs at ~8 weeks gestational age
While the bowel is within the umbilical cord, the midgut rotates 90 degrees counter-clockwise (facing the embryo). At approximately 10-11 weeks the abdomen enlarges and the intestines return to the abdominal cavity. The midgut then rotates an additional 180 degrees counter-clockwise, fixing to the posterior retroperitoneum.

Question 13

what does the cloaca contribute to

Answer 13

both the hindgut and urogenital system