Relationship between changes in the photoperiod and proliferation of Ehrlich ascitic tumor cells.

The effect of changed photoperiod (constant darkness) on the proliferation of Ehrlich ascitic tumor cells was demonstrated. Some mechanisms maintaining the proliferative homeostasis in Ehrlich ascitic tumor under conditions of constant darkness were studied, explaining more leveled pattern of circadian rhythms of cell proliferation in animals kept under conditions of constant darkness and indicating the existence of circadian rhythm in sensitivity of Ehrlich ascitic tumor cell to permanent darkness.