CHEMICAL CHANGES L\ IRRADIATED NERVE CELLS 



435 



Fig. 4. 0.075 mm beam: 180.000 rad. 30 hours sur\-ival. Cerebellum. Note the 

 degree of enzyme activity in the different layers, (M) molecular layer, (P) Purkinje 

 cell layer, (G) granule cell layer, and ( W ) white matter. Frozen section. Holt's tech- 

 nique for esterases, blocking with DFP. counterstained with Oil Red "O". 



Discussion 



One cannot overlook the marked difTerence between the activity of A-type 

 cathepsins as elicited by small and lar2,e diameter beam irradiations. While 

 the path of 0.075 mm beams is sharply outlined by the blue indi«o formed by 

 the enzymes, the 0.250 mm beam path, after an almost identical dose and 

 survival time, displays only sporadic evidence of increased enzyme activity. 

 Furthermore, in the lesions produced by the small beams, the enzyme activity 

 is found just as often in the nerve cell cytoplasm as in the interstitial elements, 



