108 SCHJEIDE, YAMAZAKI, CLEMENTE, RAGAN AND SIMONS 



Although in this preliminary survey no difTerences could be detected be- 

 tween irradiated and control cortices (and cerebellums) in terms of relative 

 lipid, relative phospholipid, and relative nitrogen, irradiated brain stem 

 apf)eared to contain relatively less total lipid beginning at about 14 days fol- 

 lowing exposure. The inhibition of lipid synthesis in the brain stem (failure 

 of myelination) was accompanied by a parallel retardation of the dehydra- 

 tion normally occurring as a function of age. 



Some tissues from irradiated brain revealed decreases in wet volumes of 

 mitochondria. In no case was there a significant increase of mitochondria in 

 irradiated tissue. 



The ratio of palmitic acid to stearic acid and to oleic acid in the nuclei 

 decreased as a function of age. The de\elopment of this ratio was retarded 

 in the irradiated tissues examined. 



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