| 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 |