[State of the temporal organization of the system of cell reproduction in rat tissues under hypokinesia].

The study of time parameters of cell kinetics in the rats exposed to 34-day hypokinesia showed that changes in cell reproduction developed in rapidly and slowly renovating cells in a different way. The DNA synthesis and mitotic division were drastically inhibited in liver cells; the duration of the premitotic period of the mitotic cycle was significantly reduced in the cryptal epithelium of the small intestine. Hypokinesia did not cause important changes in the phasic structure of diurnal rhythms of cell division in the tissues tested and, consequently, did not lead to changes in the mechanisms of time organization of the cell reproduction system. It is concluded that the state of motor activity of animals is not the major time cue for cell division processes.