1036 



RADIATION BIOLOGY 



gested by Jacobson, Marks, and Lorenz (1949) that it may represent a 

 multiplication of cells that were injured at the time of irradiation and 

 that died after a limited number of divisions. Cells of the granulocyte 

 series, which are grossly abnormal morphologically, are found in the 

 peripheral blood and in the bone marrow (Bloom, 1948; Bloom and 

 Jacobson, 1948) during this period. The temporary increase in these 

 various cell types in the peripheral blood parallels temporary waves of 



— •- 



_L 



J_ 



_L 



_L 



6 8 



10 12 14 16 18 20 22 24 26 28 30 32 34 



TIME AFTER X RAY, doys 



8 6 4 2 2 

 PHENYLHYDRAZINE 

 ADMINISTRATION 



©— © PHENYLHYDRAZINE AND 800 r OF TOTAL-BODY X IRRADIATION 



• • CONTROLS. o— • PHENYLHYDRAZINE ONLY 



o— — o 800 r OF TOTAL-BODY 

 Fig. 16-4. Effect of a single dose of 800 r of total-body roentgen irradiation on the 

 reticulocyte values in the peripheral blood of normal rabbits and rabbits with a 

 phenylhydrazine-induced anemia. {Originally published in Science, 107: 249, 1948.) 



regeneration observed histologically by Bloom and Bloom (1947) and 

 Bloom (1948) in the bone marrow especially after radiation injury. 



Radiation-induced Anemia. Red-cell precursors (erythroblasts) have 

 been described by Bloom and Bloom (1947) as being the most sensitive 

 to irradiation injury of all the cellular elements of mammalian bone 

 marrow. This conclusion is based on histologic evidence of the degree of 

 destruction of the erythroblasts in comparison with that of other cell 

 types such as granulocyte precursors and megakaryocytes. These 

 observations were made on mice, rats, chickens, and rabbits exposed to 

 30-day LD &0 dosages and those well below this range. In fact it has been 

 suggested by Bloom and Bloom (1947) that the sensitivity of erythro- 

 blasts is comparable to that of the lymphocyte. It must be pointed out, 

 however, that Bloom compared only the immediate morphologic response 



