Entodermal derivatives: formation of the gut, liver, and pancreas |
Folding forms the gut |
Cephalocaudal and lateral folding occur simultaneously |
Flexion delimits the bowel |
Anterior-posterior and lateral folding form the primitive gut |
The dorsal mesentery thins to allow the gut to be flexibly suspended |
The foregut has many derivatives |
Esophagus elongates rapidly |
Obliteration of the lumen and recanalization occurs |
The stomach rotates 90° in a clockwise direction |
Rotation of the stomach creates the lesser sac |
Rotation of the stomach forms the omental bursa |
Movements of the mesentery and stomach are made possible by vacuolization due to selective apoptosis |
Liver, biliary system and pancreas arise from the duodenum |
Hepatic diverticulum grows from the duodenum into the ventral mesentery |
Ventral mesentery forms falciform ligament, hepatic peritoneum, and lesser omentum |
Ventral mesogastrium supports liver and stomach |
Rotation of the stomach shapes the pancreas |
Aberrant rotation causes an annular pancreas |
Review of the Gut Tube |
Derivatives of the midgut |
The midgut grows rapidly and herniates into the umbilical cord |
Slide 23 |
The midgut rotates around
an axis of the superior mesenteric artery: 1. 90° 2. 180° |
Rotation of the midgut |
Loops of bowel fuse with the body wall and become secondarily retroperitoneal |
Slide 27 |
Volvulus is a serious complication of excessive flexibility |
Slide 29 |
Derivatives of the hindgut |
The hindgut is originally a cloaca-partioned to form rectum and urogenital sinus |
Urorectal septum divides the cloaca |
Hindgut forms superior 2/3 of rectal canal; proctodeum forms lower 1/3; divided at pectinate line |
Never forget the pectinate line |
If anything can go wrong it will; anorectal malformations |
The END |