[State of hematopoiesis during irradiation simulating radiation exposure in prolonged space flight].

The paper presents the results of studies of the peripheral blood and bone marrow of 36 male dogs exposed to a chronic 3 year gamma-irradiation (from the Co60 source) at a dose rate of 0.17 rad per day which was combined with acute irradiations. The animals received two doses -360 and 564 rad in total. The leukoblastic system showed inhibition and decreased reactivity in case of irradiation with a higher dose. The red blood cell balance remained stable for a long period of time due to activated erythropoiesis.