HEMATOLOGIC EFFECTS OF RADIATION 



1041 



days; recovery (if the exposure was in the LD 50 range) is usually com- 

 pleted in three to four weeks. With dosages above the LD 50 the anemia 

 develops more precipitously and is more severe, and the recovery process 

 is delayed. 



The immediate precursors of the erythrocyte are not significantly 

 reduced in number in the peripheral blood of rabbits (Jacobson and 

 Marks, 1947) and rats (Lawrence and Lawrence, 1930) with doses below 

 100 r. With doses above 100 r, reduction in reticulocytes becomes 



10 20 30 40 



TIME, days 

 O 220 r «260r A 310 r D 360 r • 420 r 



Fig. 16-7. The effect of single doses of total-body roentgen irradiation on the red-cell 

 count, hemoglobin, and reticulocyte values of hybrid guinea pigs. 



progressively more significant in all the common laboratory animals. 

 Doses in the LD 50 range reduce the reticulocytes from a normal of 1-4 

 per cent to less than 0.1 per cent. Recovery after such exposure begins 

 at about the same time in the various species. As illustrated in Fig. 16-4, 

 a compensatory elevation above the normal range occurs as recovery of 

 erythropoietic tissue proceeds. 



SINGLE EXPOSURE TO FAST NEUTRONS 



Lawrence and Lawrence (1936) and Lawrence, Aebersold, and Lawrence 

 (1936) reported the first study on exposure of mammals to fast neutrons. 



