Influence of restricted diet on the cell cycle in the crypt of mouse small intestine.

Previously we reported that the small intestine of mice adapted to dietary restriction had low mitotic acitivty in the crypts. In that case there was no marked difference in the villus and crypt cell numbers, but the migrating speed from crypt to villus decreased, consequently the transit time was prolonged. The present study was undertaken in order to clarify whether or not the cell cycle of the proliferative cells in the crypts alters when the mitotic activity decreases. The results obtained in this study indicate that: 1) There are differences in cell cycle and labeling index between the unrestricted animals and restricted animals. 2) The cycle time of the duodenal and jejunal cells, particularly of G1 phase was prolonged under dietary restriction. 3) The prolongation of cycle time was not found in the ileum. It is thought that the proliferative cell number principally controls mitotic acitivity in the crypts. Still, reduction of the proliferative cell number will be accounted for by the increase of resting cells in G1 phase.