270 H. HAGER, W. HIRSCHBERGER AND A. BREIT 



Mi; : • ■ . ,:-= cp 



-^ r ^ . . . ' . • . • • ^ ^ V -' 



^ ' \. ' ! . -'' X CM 



• .> • 



J. • ^ 



y 



Fig. 11. Cerebral cortex, 172 hr after exposure to 7,500 r. Interruption of nuclear 

 (NM) and cytoplasmic (CM) membranes of a nerve cell with breakdown of internal 

 arrangement of mitochondria (Mi). Severe changes in appearance and distribution of 

 nucleoplasm (Np) and cytoplasm (Cp). X 21,600. 



as in Fig. 12, are also strikingly alteied. One can recognize enormous swell- 

 ing of the endothelial cytoplasm, vaciiolation, and various types of inclusion 

 bodies, so that these cells appear to have a phagocytic function. The base- 

 ment membrane remains relatively well preserved. In Fig. 13, at the border 

 zone of a necrotic area, two large reactive astrocytes are seen. The cytoplasm 

 of these cells is clearly of the same type as the pale, watery cytoplasm that 

 previously has been considered characteristic for astrocytes (Farquhar and 

 Hartmann, 1957; Schultz et ai, 1957). The presence of intracytoplasmic 

 fibrils in these cells, which can be seen in Fig. 14 at higher magnification, 

 would seem to be a significant point in the positive identification of this cell 

 type as an astrocyte and not as an oligodendrocyte as has been maintained 

 by some investigators (Briinner, 1920; Luse, 1958). 



