[Participation of different cell populations in the mouse esophageal epithelium in the formation of a circadian rhythm of proliferation].

Investigation of the variations in the index of labeled mitoses throughout 90 hours after a single injection to mice of 3H-thymidine at 01 or at 13 o'clock (the periods of the maximal and minimal labeling index in the circadian rhythm of cell proliferation) showed that the cell population which had completed synchronously the mitotic cycle during the first day of experiment also plays the main role in the formation of the peak rhythms in the mitotic index in the following days. The capability of a part of the synchronous population cells to preserve high proliferation rate during several days may be accounted for by the fact that the duration of the mitotic cycle of these cells is comparable with the duration of the rhythm period. The contribution of the asynchronous population into the formation of the peak rhythms in the mitotic activity is insignificant. However, this population proliferates actively enough during the periods of the decreased mitotic index.