184 



ORVILLE T. BAILEY 



Fig. 12. Clollagen production in the depths of an area of radiation necrosis at a 

 stage before proliferation of astrocytes has begun. Gallocyanin-van Gieson X250. 

 Dosage 600 r Ta'"" in 8 days to right corona radiata. Mild hemiparesis developed. 

 Sacrifice 20 days after completion of radiation. Area of necrosis 7 mm in diameter. 



Radiation Reactions in Other Structures 



In the acute phase of the radiation reaction in menins^es, inflammatory 

 changes with polymorphonuclear leucocytic infiltration are conspicuous with 

 doses of 300 r or larger. The process is localized with smaller doses, but tends 

 to spread more widely as the dose is increased. At longer intervals after 

 radiation, the cellular infiltrate becomes mononuclear with some connective 

 tissue proliferation. Vascular lesions occur within the meninges and undergo 

 the same secjuences as those within the brain parenchyma (Clemente ct al., 

 1960; Haymaker et al., 1958; personal material). 



In the choroid plexus inflammatory changes similar to those in the menin- 

 ges are present in the acute phase, occasionally accompanied by small hemor- 

 rhages. The end result of these changes is a small fibrous scar. All portions of 



