Lecture Thursday August 30: GI embryology I

Epithelium of the gut tube (epithelium of GI glands) = Endoderm
Smooth muscle, connective tissues, blood vessels = Splanchnic Mesoderm

Primitive gut tube divided into Foregut, Midgut and Hindgut

FOREGUT
- esophagus
- stomach
- liver, gallbladder and biliary systems
- pancreas
- proximal 1/2 duodenum
All supplied by branches of Celiac Trunk

MIDGUT
- distal 1/2 of duodenum
- jejunum
- ileum
- ascending colon
- proximal 2/3 transverse colon
All supplied by branches of Superior Mesenteric Artery

HINDGUT
- distal 1/3 transverse colon
- descending colon
-sigmoid colon
- rectum
All supplied by branches of the Inferior Mesenteric Artery

Arterial Anastomoses
- Foregut-Midgut junction: pancreaticoduodenal arteries link the celiac (gastroduodenal) and superior mesenteric
- Midgut-Hindgut junction: middle and left colic arteries link Superior Mesenteric and Inferior Mesenteric arteries

Dorsal and Ventral Mesentery
The gut tube is suspended from the body wall by the mostly complete Dorsal Mesentery and the partially complete Ventral Mesentery



Liver develops from a bud of the gut tube in the ventral mesentery.
Pancreas develops from buds of the gut tube into the dorsal mesentery.

Greater omentum derived from dorsal mesentery
Lesser omentum derived from the portion of the ventral mesentery between liver and got tube (stomach)
Falciform ligament derived from the portion of the ventral mesentery between liver and ventral body wall




Rotation of the stomach and shifting of the liver to the left creates the greater and lesser sacs and the omenta

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