Changes in hemopoiesis of mice during chronic irradiation with a dose rate of 957 mGy/day

Quantitative and qualitative changes in the blood producing organs and in the peripheral blood of mice were evaluated. The animals have been continually irradiated for 42 days with a daily dosage of 957 mGy. Until the 7th day of irradiation a significant diminution of the cellularity of the bone marrow and of the cellularity as well as the mass of the spleen could be observed. After the 14th day of irradiation a temporary stabilization of the cell number in the bone marrow could be found until the 28th day, after that time there was a moderately strong decrease. The cellularity and the mass of the spleen increased temporarily until the 28th day of irradiation owing to the increase of erythropoiesis and myelopoiesis from 20% to 50%. The most significant changes in the peripheral blood could be observed in agranulocytes as a kind of sudden and permanent decrease. The diminution of the granulocyte and reticulocyte numbers proceeded somewhat more slowly, with a temporarily increasing tendency on the 28th day of irradiation. The erythrocyte numbers as well as the hematocrit and hemoglobin values decreased continually beginning from the 7th day of irradiation until the death of the animals. (author)