[Changes in mouse erythropoiesis during continuous irradiation with a daily dose of 957 mGy]

Quantitative and qualitative changes in the blood producing organs and in the peripheral blood of mice are evaluated in this paper. The animals were irradiated for 42 days continually 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 or 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 because of erythropoiesis and myelopoiesis increasing from 20% to 50%. The most significant changes in the peripheral blood could be observed in not granulated cells as a kind of sudden and permanent decrease. The diminution of the granulocyte and reticulocyte number proceeded somewhat more slowly, temporarily revealing an increasing tendency on the 28th day of irradiation. The erythrocyte numbers as well as the haematocrit and haemoglobin values decreased continually beginning from the 7th day of irradiation until the death of the test animals.