EFFECTS OF HIGH-DOSE RADIATION ON BRAIN 



253 



fragmentation in some (Figs, la, b). Macrophages, with phagocytized cellu- 

 lar debris, were present. Notable losses of granule cells became evident in 

 animals killed 8 days after exposure, and a mild astrocytic proliferation was 

 present at this time. Golgi and Purkinje cells remained intact i Fig. 2). 



Vasculitis 



An exudate of leucocytes appeared promptly in all layers of the cerebral 

 blood vessels. Veins and arteries were invoked about equally. Vessels of all 

 sizes were affected. The vessels in the cerebral nuclear masses were generally 

 more intensely involved than those in the cerebral cortex, while those in the 

 white matter shared in the process, but to lesser degree. The vessels of the 

 brain stem, cerebellum, and spinal cord were similarly affected, also in lesser 

 intensity. The leucocytes rarely penetrated into the surrounding neural sub- 

 stance, but usually concentrated in the ad\entitia and perivascular spaces. 

 Hemorrhage was rare. Vessels stained specifically for collagen and elastic 

 tissue regularly showed no notable alterations in these components. With 





Fig. 2. The rarified granular layer of a dog 10 days after exposure to lo.OOO r of 

 gamma radiation contains CJolgi cells and an increased number of astrocytes, but is 

 largely devoid of granule cells. Hemato.xyiin and eosin stain. X 55. 



