The morphological and functional differentiation of the alimentary canal of the pig during ontogeny. II. Development and differentiation of the jejunum.

Morphological development and differentiation of the pig's jejunum during ontogenesis were studied. It was found that villi intestinalis are formed on about the 40th day of embryogenesis. The differentiation of absorptive epithelium, goblet cells and argentaffine cells as well as the formation of the Lieberkühn's crypts, and muscularis mucosae, occur by the end of the 2nd and at the beginning of the 3rd month of the prenatal development. The Paneth cells are found in the period around birth. After birth there is an adaptive rearrangement of the mucosa of jejunum affecting both the epithelium and the propria: the rearrangement is conditionally divided into two periods - from birth to the 3rd day, and from the 10th to the 20th day.