PATHOLOGIC CHANGES IN BRAIN CAUSED BY ALPHA PARTICLES 391 





^^H^^^^ . 





Fig. 5. Alpha particle radiation, 1L!,000 rad surface dose: sacrifice at 24 hours. 

 A fairly sharp border separates irradiated from nonirradiated granular layer. Above 

 this border the density of pyknotic granule cells decreases progressively. The Purkinje 

 cell (arrow) at the lower border of the damaged granular layer, i.e., in the most 

 intensely irradiated region, shows an alteration in nuclear chromatin. Cells in the 

 corresponding region of the molecular layer appear unaffected. Vessels are not dilated. 

 X175. 



nuclei of occasional cells, piesiimablv nerve cells, were extraordinarilv en- 

 larged ( Fis;. 4B ) . By contrast, no exidcnce of damage was obser\ed in the 

 cerebellum. 



At the 3,000 rad sinface dose, with sacrifice at 4 to 216 days i Table I), 

 two brains studied at 20 davs had a narrow band of "ranule cell rarefaction 



