Gastrointestinal Embryology

The abdominal organs are derived primarily from endoderm, which forms the primitive gut tube. The gut tube is divided into 3 regions: foregut, midgut, and hindgut. The foregut gives rise to the lining of the GI tract from the esophagus to the upper duodenum, as well as the liver, gallbladder, and pancreas. The midgut gives rise to the GI tract lining between the midduodenum and midtransverse colon. The hindgut gives rise to the GI tract lining from the midtransverse colon through the upper anal canal. The mesoderm gives rise to the muscles of the GI tract wall, connective tissue (including the mesenteries and omenta), and the vasculature. The ectoderm gives rise to the nerve tissue and the lining of the lower anal canal.