NEUTRON EFFECTS ON ANIMALS lo' 



ological changes in groups of 10: 1, 2, 4, 5, 7, 10, 14 and 20 days after 

 irradiation. All sections appeared normal. , , . , . 



The kidnevs of the 80 rats used for study of histopathological changes 

 in liver were examined microscopically. No histopathological changes were 



°^D7solion. Liver and kidneys are examples of organs which appear 

 to be e" istant to neutron radiation, so far as histopathological observations 

 eveal Although these organs did not appear to be affected structurally, 

 he possibility exists that their functions, especially those of the iver, may 

 have been aiTected, as suggested by Chrom (9) who concluded that, after 

 xln-adiation of mice, the phagocytic power of fixed phagocytes ,n the hver 



was lowered. 



Bone Marrow 



Rats used in the studies of the effects of neutron radiation on testes and 

 snleen were utilized. All of the marrow from one femur of each rat studied 

 was fixed in Bouin's fluid. Sections were stained with hematoxyhn and 



eosin. Seven normal rats were used as controls. 



"ITs n 15 rats. One specimen was taken at each of the following 

 periods: 1, 2, 4, 8, 16, 24, 32, 45, 60, 75, 90, 100, 120 150 and ^^^^-y^^ 



No change in structure in the marrow was found 6 hours aftei 

 irradiation. One day after irradiation young cells, probably of the granu- 

 locytic series, appeared to be slightly less numerous. There was a cor- 

 esponding pi'ominence of foci of cells with small pycnotic nuclei probably 

 cells of the erythroblastic series. These changes were shght and persisted 

 for about 3 days, after which the marrow resumed a normal appearance. 



sZ n. 22 rats. Specimens were taken immediately following and up 



to 191 days after irradiation. . .. ..^ 



No definite changes were found during the first 8 hours after irradiation. 



After 8 hours there was a shght pycnosis of megakaryocytes and the eryth^ 



roblastic foci were shghtly prominent. Specimens taken 22, 24 40, 48 



and 72 hours after irradiation showed a progressive diminution in the 



number of megakaryocytes and cells of the granulocytic series. The 



Ziges at 4 and 8 days were characterized by widening of the smuses and 



appearance of fatty tissue as other marrow elements ' f PP^^^.-^^^^^^P^ 



of cehs with dense staining round nuclei, presumably be onging to he 



ervthroblastic series, were relatively prominent and also ^^^owed a Ight 



absolute increase. There was no blood pigment or evidence of eel divisiom 



Regeneration was first evident in 16 days after irradiation when all elements 



of hematopoietic tissue were active and solidly filled the marrow spaces. 



Specimens examined at subsequent intervals were normal. 



srMMART 



Exposure of white rats to neutron radiation produced reduction in size 

 and degenerative changes in the testes characterized by cessation of mitotic 



