Autoradiographic studies on the cell kinetics after the whole body X-irradiation. 1. The mode of death in lethally damaged proliferating cells of the rat brain subependimal zone

Subependymal cells of brain of Wistar line rats, which have received 3H-thymidine 60-80 min before whole body X-irradiation in a dose of 50, 150 or 300 R are studied. According to the increase in time of the part of labelled cells including the ones with pycnotic nuclei and according to double decrease in the label intensity in the latter it has been shown that lethally damaged cells subjected to irradiation in phases G2 and S died in mitosis of the first post-irradiation mitotic cycle which excluded a possibility of their interphase death. Lethally damaged and survived cells started mitosis (pycnosis) having experienced one hour block, independent of the dose