Human Embryology and Teratology
Teaching text 9: Digestive system 2: The passage to the umbilical vesicle
Cephalic and caudal folds cause the endodermal passage to the umbilical vesicle to be significantly narrowed. This passage is constricted in the direction of the foregut and hindgut by the rostral and caudal intestinal portals respectively. The midgut develops from this restricted part of the endoderm.