Prenatal and postnatal differentiation of the small intestine in rat.

UNLABELLED: The gastrointestinal tract in the early prenatal development is an endoblastic mesenchyme-lined tube. The endoblast differentiates and gives origin to all epithelial structures (covering epithelium, glands). The mesenchyme develops into connective tissue, blood vessels, the smooth muscle cells of lamina muscularis mucosae and muscular tunic. Neuroectoblast cells participate in these pr…