EFFECTS OF HIGH-DOSE RADIATION OX BRAIN 



255 



Fig. 3. Granule cells of the cerelH-Uuin of a 3-day-old mouse grown for lU days in 

 tissue rulturc. The cells ha\c rounded nuclei with extremely scant perikaryon. Phase 

 Microscopy. X 1200. 



astrocytes. Fewer cells had a lars^er nucleus, usually with a prominent 

 nucleolus, and abimdant perikaryon that formed a sinole dominant process 

 and occasionally lesser ones. These cells were identified as neurons derived 

 from the cerebellar cortex from regions other than the s;ranular layer. 



Preliminary studies have made it clear that only cells with the cytologic 

 characteristics attributed to the granule cells showed notable structural 

 changes in the immediate postirradiation period. These changes closely 

 resembled those noted pre\iously in histologic preparations of the irradiated 

 cerebellar cortex, being characterized by a contraction of the nuclei to 

 approximately ~/i normal size. The perikaryon that was normally scant 

 about the granide cells in tissue culture became conspicuously wnder and 

 the over-all dimensions of many cells increased (Fig. 4). As noted in sections 

 stained by hematoxylin and eosin. the nuclei were contracted and the 

 chromatin material compressed and hyperchromatic. The perikaryon was 

 more abimdant than normal, stained intensely with eosin, and it was often 

 foamy and \acuolated. Altered cells were most abimdant 24 hours after 

 exposuie. Periodic examinations ot the cultures with the phase microscope 



