EFFECTS OF rilGH-DOSE RADIATION ON BRAIN 



257 



Mitochondria were small and sparse, rarely more than 6 in a single cross 

 section of a cell. Their cristae were delicate and inconspicuous. The endo- 

 plasmic reticulum was also scant, but was most abimdant at the axon hillock. 

 A Golgi apparatus frequently occupied this region. Many granule cells lay 

 side by side with cytoplasmic membranes in apposition. Others were encased 

 in part or totally by dendritic processes (Fig. 5). 



The earliest recognizable cytologic changes, abundantly evident in the 

 tissues of rabbits examined 24 hours after exposme, were characterized by 

 a contraction of the nucleus and clumping of the intranuclear granules, 

 with increased serration of the nuclear membranes and broadening of the 

 cytoplasmic space with dispersion of the cioplasmir constituents. With 







■^^ ;* 











Fig. 5. \ normal granule cell of a rabbit is encasrd in dendrites and has scant 

 cytoplasm ( f ) with few mitochondria and sparse endoplasmic reticulum, .\pproxi- 

 mately X 18.000. 



