Embryology of the Gut Flashcards
18 days
Midgut with yolk sac and yolk stalk
1 month
Yolk sac getting smaller
What does the Yolk Stalk become?
Omphalomesenteric/Vitelline Duct
What type of Peritoneal cavity is present at 18 days?
A paired peritoneal cavity
What are the parts of the Primitive Mesentery?
- Dorsal Mesentery
2. Ventral Mesentery
What parts of the Primitive Mesentery Disintegrate?
The Ventral Mesentery of the Midgut and Hindgut
5 weeks
Foregut
- Liver Growth
- Stomach: Growth rate change, Rotation 90 degrees clockwise, Displacement of stomach by liver
- Duodenum forms loop and rotates, moving to posterior body wall
What happens to the Left and Right Vagus nerves as the stomach rotates 90 degrees?
- The Left Vagus moves Anteriorly
2. The Right Vagus moves Posteriorly
What forms the Greater Omentum?
The stomach rotating 90 degrees clockwise and displacement of stomach by the liver
6 weeks
Midgut
- Rapid Elongation (Axis: Sup. Mesenteric Artery, Apex: Vitelline/Omphalomesenteric Duct)
- 180 degree counter-clockwise rotation
- Coiling Phenomenon
- Umbilical Herniation
12 weeks
Midgut
- Vitelline/Omphalomesenteric Duct Disintegrates
- Intestines return to abdominal cavity in set order and position
After birth
Hindgut
1. Descent of Cecum/Elongation (Moves from URQ to LRQ)
Malrotation
- Many variations
- Ex: Colon on Left and Small intestine on Right, Transverse Colon posterior to Duodenum
Meckel’s Diverticulum
- Vitelline/Omphalomesenteric Duct does not disintegrate
- 2:2:2 Rule (2% of cases, 2 inches long, 2 feet from Cecum (into Ileum))
Complications of Meckel’s Diverticulum
- Vitelline Duct ties diverticulum to umbilicus causing bowel obstruction
- Vitelline Fistula
- Vitelline Cyst
