PATHOLOGIC CHANGES IN BRAIN CAUSED BY ALPHA PARTICLES ;393 



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Fig. 7. Ner\'e cell changes at early stages following irradiation at the 6,000 rad 

 surface dose level. A. (6 hr) .\lpha particle radiation. Cerebellum, showing a fairly 

 broad row of pyknotic granule cells in the region corresponding to the Bragg peak. 

 Purkinje. Golgi. and Bergmann cells at this level appear unaltered. X675. B. (6 hr) 

 Proton radiation. Cerebral cortex, showing a pyknotic cell, judged to be a ner\e cell 

 which has undergone advanced necrosis. X675. C. (24 hr) Alpha particle radiation. 

 Cerebral cortex in the region of the interhemispheric fissure (which is to the left, 

 outside the field illustrated). Some ner\-e cells ha\'e \anished. and those that remain 

 exhibit a varying reduction in the amount of nuclear chromatin. Some of the nuclei 

 are "skeletonized." X375. \'an Gieson-hematoxvlin stain. 



