The epithelium of the gut and glandular cells of associated GIT glands develop from Endoderm. The endoderm also gives rise to specific parenchymal cells such as Hepatocytes and both the exocrine and endocrine cells of the pancreas.

Connective tissue, muscle tissue, mesothelium, and peritoneal components of the gut wall are derived from Splanchnic Mesoderm. The enteric nervous system develops from Neural Crest Cells.

Cephalocaudal and lateral folding incorporates endoderm to form the primitive gut. The Yolk Sac and allantois remain extraembryonic. The primitive gut consists of:
— Foregut: from the buccopharyngeal membrane to the transverse septum.
— Midgut: communicates with the vitelline tube and yolk sac; situated above the ductus omphalomesentericus.
— Hindgut: communicates with the allantoic diverticulum and extends to the Cloacal Membrane.