Comparison of the level of mitotic activity and duration of mitosis in normal and neoplastic mouse tissues during the 24-hour period

Diurnal rhythms of cell division in the epithelium of the forestomach and in a transplantable carcinoma of the forestomach were found to be largely similar and the duration of mitosis in both these tissues varied during the course of the 24-hour period. The mean diurnal mitotic activity in the tumor was twice as high as in the normal forestomach. By contrast, in the course of 24 h colchamine (colcemid) led to the accumulation of 121.1 of mitoses, compared with only 83.8 in the carcinoma. The larger number of mitoses in the tumor when counted in the ordinary way can be explained by the 2.7 times greater mean diurnal duration of mitosis in carcinoma of the forestomach than in the normal epithelium of the forestomach.Laboratory of Chronobiology, Scientific-Research Center, N. I. Pirogov Second Moscow Medical Institute. (Presented by Adademician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 11, pp. 1363–1365, November, 1976.