Different radiosensitivity of hematopoietic cells in chick-embryos

Embryos of different ages from 24th to 120th hour of incubation were irradiated with a dose of 700 R gamma rays at a rate of 50 R/min. After irradiation peripheral blood was taken every 24 hours in order to control proliferation dynamics of megaloblastic and normoblastic cells. The results have shown that the cells of megaloblastic strain reduce much more the mitotic activity that those of normoblastic line. Although the cells of both strains after irradiation show depression in the proliferative activity, in transfer to polychromatophilic forms, megaloblasts disappear almost completely until normoblasts recover spontaneously. The nature of different radiosensitivity in these cell strains has been discussed.