HISTOPATHOLOGY OF CNS RADIATION 175 



changes in close association with the cerebellar lesions: the alterations in the 

 grannie cells are regarded as direct effects of radiation. 



Campbell ct al. (1946), on the other hand. ha\e found early changes in 

 Purkinje cells. Haymaker et al. { 1958) have noted somewhat similar changes 

 in Purkinje cells, but also have found these types of alteration in a control 

 monkey. Nerve cell bodies in other regions of the ner\ous system are little 

 affected in the acute phase of the radiation reaction. Brownson (1960), in 

 determining whether any effects on these structures can be detected by 

 changes in the perineuronal satellite cells, found no statistically significant 

 alteration in neuron-neuroglia relationship ot the cerebral cortex alter 

 1,600 r. 



Though less extensi\ely studied, beta radiation apparently exerts an effect 

 directly on the nerve cells (Campbell and No\ick. 1949). 



Delayed necrosis of the para\entricular and supraoptic nuclei of the hypo- 

 thalamus has been demonstrated by Arnold 1 1 al. ( 1954b) . This is a specific 

 effect and is produced by doses of 3.000 r or less, no radioselectivity being 

 noted with larger doses. CMemente and Hoist (1954) also have encountered 

 consistent inxohement of the hypothalamus. 



There is a high degree of radioselectivity for the white matter ' Arnold 

 et al., 1954b I. The neuronal necrosis becomes progressively more e\ident as 

 the interval between radiation and sacrifice of the animal is lengthened. 4'his 

 delayed reaction is one of the most striking differences in histology between 

 the acute and late phases of radiation change. 



An extensixe literatiuc is in almost complete agreement that the brainstem 

 is the most sensiti\e region (Arnold et al.. 1954a, b. c: Colwell and Glad- 

 stone. 1937: Demel. 1926: Ellinger. 1942: Ellinger and Davison. 1942: 

 Mogilnitzky and Podljaschuk. 1928). Hicks and Montgomery (1952) also 

 describe special sensiti\ity in parts of the ""oltactory brain."" At least in the 

 dosages generallv used, the injurv tf) the brainstem in\ol\es both white and 

 gray matter. In fact. C'.olwell and Gladstone i 1937 ) emphasize ner\e cell 

 changes in these regions and in the central gray matter of the cerebrum. 



Personal material, using the monkey spinal cord, is in accord with the 

 literature cited in regard to late effects on the neuron. The nerve cell bodies 

 in both anterior and posterior horns show no detectable changes after extra- 

 dural application of Ta'""-' or roentgen ladiation. except when in an area of 

 total necrosis. 



Nerve fiber necrosis in the posterior portion of the spinal Cf:)rd is iiregular. 

 but widely distributed, and extends little beyond the immediate zone ot 

 radiation, either with Ta'^- or roentgen radiation. In the monkeys sacrificed 

 in less than 2 weeks after completion of radiation, the only change found was 

 occasional myelin degeneration in isolated segments. In later stages, the 

 <'xtent of mvelin defeneration is somewhat greater than that of demonstrable 



