Effect of vitamin A deficiency on intestinal cell proliferation in the rat.

Cell division kinetics and the biochemical composition of the small intestine of normal and mildly vitamin A-deficient rats have been examined. Thymidine labeling index, growth fraction and the content of DNA, RNA and protein in the jejunal mucosa were not significantly affected by vitamin A deficiency. On the other hand, the duration of the cell cycle of jejunal crypt cells was found to be lengthened by vitamin A deficiency and this increase in generation time was due mainly to a lengthening of the DNA synthesis phase. Furthermore, the labeling pattern of the newly divided crypt cells of the vitamin A-deficient rats was strikingly different from that of the vitamin A-supplemented rats, suggesting an impaired migration of cells out of the crypts. These findings suggest that vitamin A may play a role in the regulation of cell division in the small intestine of the rat.