TBL16 - Gut Tube

Question 1

What surrounds the gut tube endoderm? What are derivatives of this layer?

Answer 1

1) The gut tube endoderm is surrounded by visceral mesoderm

2) Thus, connective tissue and smooth muscle of the tubular wall are derivatives of the visceral mesoderm

Question 2

What does the gut tub consist of? What initially opens to the yolk sac via the vitelline duct? What are foregut derivatives?

Answer 2

1) The gut tube consists of the cranial foregut, caudal hindgut, and midgut, which initially opens to the yolk sac via the vitelline duct
2) The esophagus, stomach, and proximal duodenum are foregut derivatives

Question 3

What other structures are derived from the foregut? How do they arise? What forms the rest of the gastrointestinal (GI) tract?

Answer 3

1) The gallbladder, liver, and pancreas are foregut-derived
2) They arise as endodermal buds from the proximal duodenum
2) Derivatives of the midgut and hindgut form the rest of the gastrointestinal (GI) tract

Question 4

What supplies the foregut, midgut, and hindgut derivatives?

Answer 4

The celiac artery, superior mesenteric artery (SMA), and inferior mesenteric artery (IMA) are unpaired branches of the abdominal aorta that supply the foregut, midgut, and hindgut derivatives, respectively

Question 5

Where do the vitelline veins pass through? What does the liver bud develop into? After draining the duodenum, where do the right and left vitelline veins travel and what do they form?

Answer 5

1) The vitelline veins pass through the septum transversum en route to the sinus venosus
2) After arising from the duodenum, the liver bud grows into the septum transversum
3) Therefore, after draining the duodenum, the right and left vitelline veins enter the liver to form the hepatic sinusoids and hepatic veins

Question 6

What occurs after formation of the left-to-right venous shunt? What does the right vitelline vein become?

Answer 6

1) After formation of the left-to-right venous shunt, the distal portion of the left vitelline vein disappears
2) After generating the superior mesenteric vein, the enlarged right vitelline vein becomes the hepatic portal vein

Question 7

What drains into the hepatic portal vein? What percentage of blood flow to the liver does this account for?

Answer 7

Venous blood from the entire GI tract and the spleen drains into the hepatic portal vein, which provides 80% of blood flow to the liver