NON-NEOPLASTIC LATE EFFECTS 



187 



the endothelial or the epithelial cells at all. It is a definite formation of the ground sub- 

 stance, and we know that there, the sensitivity to irradiation is large. The rest is specula- 

 tion. 



cottier: I should like to emphasize that the question of radiation nephrosclerosis in late 

 stages after mid-lethal doses of radiation is still very open to doubt. First, there is not 

 a 100% mcidence of this change, and, second you can observe this change also to a 

 certain extent in non-irradiated animals. As far as rats are concerned, this is another 

 problem, because these rats are apt to become hj^ertensive while other animals don't. 

 Another point is that the morphology of this particular hypertensive neplirosclerosis is 

 different from the morphology of glomerular changes m mice, at later stages of irradia- 

 tion. In the former you find an increasing thickness of the strongly PAS-positive base- 

 ment membranes, while in mice you find hyaline material — in some mice, not all — which 

 is not strongly positive for PAS. I should like to mention the paper of Rosen, which 

 appeared last year. In other strains of rats they did not find the consistent thickening of 

 the basement membrane. Their main finding was cellular changes— giant cells in glomeru- 

 lar loops and things Uke that. The only thing I would like to stress is that nephrosclerosis 

 in the later stages after whole-body irradiation with these doses in the middle range is 

 not well established. It remains to be shown whether some of these changes are actually 

 complications like the hyalme disease which has been described for mice, and other, 

 possibly infectious complications of the glomerular loops. 



brinkman: Of course this was only meant as a speculation. It might be worthwhile to say 

 that at any rate you should look at basement membranes and try to see them by special 

 methods of correlation and confirmation, because in most preparations you caimot see 

 them at aU. The preparation should be specially treated in order to be able to see them, 

 and I thmk in many researches on this topic this has not been tried. 

 trPTON: A number of workers have reported the effects of radiation on extracellular or 

 intracellular material, and such effects as the thermodenaturation of collagen are well 

 known. The question I think to which we should address ourselves is this. Can one account 

 for effects seen in vivo in the ground substance or in the basement membrane on the basis 

 of radiation effects on extracellular materials predominantly, or could it be supposed that 

 such effects are indirect — ascopal in a sense — mediated through cellular injuries? 



