MORPHOLOGICAL EFFECT OF X-RAYS TO THE CNS 223 



the bordering zone with granular breakdown of the astrocytic processes 

 could be observed in Cajal preparations. In the necrotic zone, it was difficult 

 to identify the different types of cells Fig. 14). Only a few nerve cells could 

 still be recognized by their acidophilic cytoplasm. In all other cells, the 

 perikaryon became unstainable. Almost all cells, including glial elements, 

 demonstrated pyknotic nuclei. Some polymorphonuclear leucocytes could 

 also be recognized. With lurther shortening of sia\i\al time to 7 hours, only 

 two small zones of spongy loosening of the tissue were seen, situated almost 

 symmetrically in both hemispheres (^Fig. 15 j. They were rather sharply 



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Fig. 15. Two sharply limited small foci of spongy loosening, symmetrically and 

 rather superficially located in the cortex. This is an early stage, 7 hours after local 

 application of 20.000 r. H. and E. 



limited by intact nerxous tissue. The cellular elements in the spongy zone 

 exhibited only minor changes, such as shrinkage with a clear nuclear struc- 

 ture (Fig. 16). Sometimes, however, groups of nerve cells showed signs of 

 dissolution, including \acuolization of the cell cytoplasm. After local irradi- 

 ation with 45.000 r and a survival time of 6 hours, small areas of sponginess 

 of tissue of the same type and size reaching from the surface to the 3rd 

 cortical layer could be obser\ed Fig. 17). The nerve cells exhibited only 

 minor chances, such as diminished affinity for gallocyanin. and leucocytes 

 were absent. With low power, this deviation can be more clearly seen as a 



