The Effect of Acute Gamma Irradiation of the Head on the Erythropoiesis in Various Regions of the Hemopoietic System in Mice

A decline of 59Fe incorporation into the heme fraction of the bone marrow of the skull to roughly 70 % of the physiological state took place in animals whose heads were irradiated with a dose of 16 Gy of 60Co-gamma radiation in the whole interval of 14-69 days post irradiation studied. A decline of 59Fe incorporation to roughly 40 % took place in the shielded (non-irradiated) bones on the 14th day, post irradiation; however, a recovery followed, reaching the initial values between the 30th and 40th days after irradiation. While the depth of the postirradiation decline is about the same in all the bone regions shielded, the acral bones showed in contradistinction to the long ones a marked overshoot above the control values (i. e., an indication of ectopic erythropoiesis) in the recovery phase. The main place of ectopic erythropoiesis was the spleen, however. The temporary decline of erythropoiesis in the shielded regions, accompanied by anemization of the animal, could be interpreted as a result of worsened nutritional conditions in the framework of the »oral postirradiation syndrome«, compensated for by a wave of regenerating erythropoiesis with the involvement of ectopic localities after the recovery of nutrition.