250 F. STEPHEN VOGEL 



formation about the pathogenesis of transitory and lethal cellular responses 

 of neurons to ionizing radiation. 



Methods 



Most procedures employed in these studies have been described in detail 

 in individual publications. 



Total body radiation was administered to 67 young, 2- to 4-year-old, 

 male Macacus rhesus monkeys, in graded doses from 1.000 to 30,000 r from 

 a Ba^^"-La^^" source, at 1,000 r per minute. Detailed morphologic examina- 

 tions were made of all animals promptly after death (Haymaker ct al., 

 1958). 



Gamma radiation, in total doses of 10,000 r, was administered at 1,000 r 

 per minute from a Go''" somce to 48 young male Macacus rhesus monkeys, 

 divided into 3 groups of 16 animals each. One group received radiation to 

 the head with the body shielded ; another, to the body with the head 

 shielded; and a third, to the entire animal. At periodic intervals up to 96 

 hours later, pairs of animals from each group were killed (Vogel ct al., 

 1958). 



Explants of cerebellar tissue from mice, 3 days old, were grown on slides 

 with prepared media (Gillete and Findley, 1958) in Garrel flasks and 

 Maximow chambers. Gamma radiation was administered in doses of 10,000 

 r from a Go"" Ticker machine at 160.5 r per minute at a distance of 30 cm. 

 Irradiated and nonirradiated cultures were examined periodically by the 

 phase microscope, and tissues were remoxed from the cultmes, stained by 

 hematoxylin and eosin, and examined by light microscopy. 



Young healthy mongrel dogs and adult white albino rabbits were exposed 

 to 15,000 r of gamma radiation from a Go''" Ticker machine over the 

 superior cerebellar region with a field 5 cm in anterior-posterior dimension 

 and 7 cm across. The rate was 160 r per minute with a source to skin dis- 

 tance of 30 cm and a half value layer of 1 1 mm of lead. Tissues were 

 taken from the cerebellum of anesthetized animals, fixed immediately in 1% 

 osmium tetroxide solution, and prepared by standard methods for electron 

 microscopy (Vogel, 1959). 



Observations 



Morphologic Effects of Gamma Radiation on the Brain as viewed 

 WITH THE Light Microscope 



Exposure of animals to massive doses ol ionizing radiation is followed 

 promptly by conspicuous morphologic alterations in the brain and mesen- 

 chyma, notably by a pyknosis of the cerebellar granule cells and inflamma- 



