Midgut

The midgut extends from the hepatic bud to the left third of the transverse colon. This is also where the innervation from the vagus nerve and the blood supply from the superior mesenteric artery terminate. In addition, this is the origin of the caudal half of the duodenum, and the jejunum, ileum, caecum, appendix vermiformis, colon ascendens and the right and middle thirds of the colon transversum.
The midgut is in direct contact with the umbilical vesicle until the end of the somitic period (S13/14). After this time, the passage between them narrows to form the omphalo-enteric duct. The entire midgut is fixed to the posterior abdominal wall by means of a short mesentery. It then grows quickly and forms the umbilical loop. In the axis of this loop is the superior mesenteric artery, which originates from the omphalomesenteric arteries. The umbilical loop has a rostral limb, a caudal limb and the omphalo-enteric duct at its apex.