[Autoradiographic study of cell kinetics after whole-body x-ray irradiation. III. A study of the postradiation changes in mitotic activity and the mitotic cycle of the subependymal cells of the rat brain].

Dynamics of the mitotic index and changes in the mitotic cycle were studied in the rat's brain subependymal cells, using autoradiography with 3H-thymidine injected 60-80 minutes before the whole body X-irradiation in doses of 50, 150 or 300 R. The "classical mitotic blocks" has been shown not be be a block of cells being in phases of the mitotic cycle; unlike, it points to the dose-dependent time of appearance of the first mitoses in cells that survived, because all the cells that had divided earlier died during mitosis. This may suggest that the post-irradiation mitotic index curve may serve a tool for counting the number of non-surviving proliferating cells. The delay in the first wave of the labeled mitosis curve dependent of the mitotic death of cells being in G2- or S-phases at the time of irradiation is discussed in addition to other peculiarities of the labeled mitosis curve.