Postnatal Development of the Small Intestine of the Rat: Changes in Mucosal Morphology at Weaning

Extract: At 15 days after birth, the small intestine of the rat showed a striking increase in relative weight, an increased depth of intestinal crypts, an elevation of the mitotic and the labeling index of crypt cells, and a decrease in the ratio of height of the villi to depth of the crypts. Metabolically, the biological half-life of 14C phenylalanine incorporated into protein was decreased in the intestine of 21-day-old rats compared with that...