[Cell population relations in the mechanism of the circadian rhythm of proliferative activity in the tongue epithelium of mice exposed to continuous light].

A single dose of 3H-thymidine was injected to mice maintained either on a 12-hour light-dark cycle (LD group) or on a long-term continuous light (LL group) at the peak of DNA synthetic activity in the tongue epithelium. The parameters of the circadian rhythm of cell division and mitotic cycle were studied. The LL group animals demonstrated pronounced asynchronization of the circadian rhythm of the mitotic index. At the same time the curves of the percentage of labeled cell populations in the LD and LL group animals appeared similar. The data suggest that asynchronization of the circadian rhythm of the mitotic index is linked with cell-population interrelations and the differences in the status of individual cell populations entering the mitotic cycle at varying times of the day.