GI Embryology II

Question 1

What does the pancreas develop from?

Answer 1

Ventral and dorsal pancreatic buds (endoderm)

Question 2

What structures in the pancreas come from the ventral side? Dorsal side?

Answer 2

Ventral: Head and uncinate process
Dorsal: Everything else

Question 3

Which pancreatic duct becomes the definitive pancreatic duct (Duct of Wirsung)?

Answer 3

Duct of the ventral pancreas

Question 4

What structures form the exocrine pancreas?

Answer 4

Acini

Question 5

What structures become the endocrine pancreas?

Answer 5

Islets of langerhans and ducts

Question 6

What structure from an ileal diverticulum

Answer 6

Omphaloenteric duct (yolk stalk)

Question 7

What structure serves as the axis for GI tract rotation during umbilical herniation?

Answer 7

Superior mesenteric artery

Question 8

What direction is the rotation during umbilical herniation?

Answer 8

270º rotation counter-clockwise

Question 9

What does histological examination of Meckel (ileal) diverticulum look like?

Answer 9

Pancreatic tissue, stomach tissue, intestinal tissue all in one

Question 10

What developmental feature is responsible for a Gastroschisis?

Answer 10

Abnormal lateral body wall folding

Question 11

What developmental feature is responsible for a congenital omphalocele?

Answer 11

Physiological umbilical herniation

Question 12

If rotation does not occur, where does the large intestine sit in relation to the small intestine?

Answer 12

To the left

Question 13

What structures are derived from the dorsal mesentery?

Answer 13

Transverse mesocolon
Mesentery
Greater ometum
Sigmoid mesocolon

Question 14

What is the cloaca?

Answer 14

Caudal end of hindgut and the base of urogenital sinus

Question 15

What does the cloacal membrane separate?

Answer 15

Cloaca from proctodeum

Question 16

What embryological tissue gives rise to the urorectal septum?

Answer 16

Mesenchyme

Question 17

What does the urorectal septum separate? What does the separated structure become?

Answer 17

Cloacal membrane into urogenital membrane and anal membrane

Question 18

The fusion of the urorectal septum and cloacal membrane becomes what?

Answer 18

Perineal body

Question 19

What derives the upper two thirds of the anal canal? The lower third?

Answer 19

Upper 2/3: Hindgut

Lower 1/3: Proctodeum

Question 20

What line separates the hindgut/proctodeum derived anal canal?

Answer 20

Pectinate line

Question 21

What vessel supplies the proctodeum?

Answer 21

Inferior rectal branch of internal pudendal

Question 22

What vessel supplies the handgun?

Answer 22

Inferior mesenteric

Question 23

Where do lymphatics from the hindgut drain?

Answer 23

Inferior mesenteric nodes

Question 24

Where do lymphatics from the proctodeum drain?

Answer 24

Superficial inguinal nodes

Question 25

What line signifies the area where anal epithelium changes from simple columnar to stratified squamous?

Answer 25

Anocutaneous line

Question 26

What cells fail to migrate, resulting in Congenital Megacolon (Hirschsprung’s disease)?

Answer 26

Neural crest cells (becoming parasympathetic ganglia)

Question 27

What results in the persistence of the cloacal membrane?

Answer 27

Imperforate anus