194 



NORBERT SCHUMMELFEDER 



At 4 to 5 hours after x-irradiation with 60.000 r. nearly all the granule 

 cells in the irradiated part of the granular layer were shrunken and their 

 nuclei pyknotic (Fig. 3). These cells were surrounded by a clear space. 

 In the molecular layer, the nuclei of the swollen nerve cells were now 

 pyknotic, while the degree of vacuolation in this part of the irradiated 

 cerebellar cortex was the same as before. The morphologic changes in the 

 molecular and granular layers were strictly localized, limited to the irradi- 

 ated field. The border betw-een the irradiated and the unchanged cere- 

 bellar tissue was sharp, as though drawn with a ruler. During this time 

 interval, the white matter of the cerebellum was slightly, if at all, modified 

 by the irradiation. There was neither detectable edema in the white matter 

 nor any substantial change in the axis cylinders or in glial cells. 



Within the first hours after irradiation, no e\idence of a conspicuous 



Fig. 3. At 4 hours after irradiation with 60,000 r, showing severe vacuolation of 

 the molecular layer, shrinkage of Purkinje cells, and pyknosis of granule ceil nuclei. 

 X 780. Hematoxylin-eosin. 



