[Average time of cell mitosis in the hematopoietic tissue of rats]

Rats (Wistar) were irradiated (60Co) with dose of 500 R at the dose-rate of 345 R/min. Using a curve of decrease of the mitotic index in hemopoietic tissue cells after irradiation, an attempt has been made to determine the average time of mitosis. The parameters (latent period, the minimum and average time of mitosis, resp., variance and density distribution type) were introduced in the mathematical equation which relates mitotic index postradiation decrease curve to mitosis time density distribution. It has been found that the actual average time of mitosis for hemopoietic tissues of rats is in the range of 25--27 min 32--33 min and 26--27 min. for thymocytes, promyelocytes--myelocytes and erythroblasts--normoblasts, respectively.