[Diurnal changes in the duration of mitosis in several tissues of young white rats].

In the acinar cells of the pancreas of 7-day rats the duration of mitosis varied from 1.7 to 2.5 hours, in the hepatocytes--from 1.3 to 5.2 and in the epidermis--from 1.5 to 2.9 hours. The 24-hour variations in the mitotic index were expressed both by the changes in the duration of mitosis and by unequal rate of the cell entrance into mitosis. The peroid of renewal of the tissues under study markedly differing in adult animals proved to be approximately the same in rats aged 7 days (12,3 days in the pancreas and 20 days in the liver and the epidermis).