EFFECTS OF IONIZING EADIATION ON CELLULAR 



COMPONENTS: 



ELECTRON MICROSCOPIC OBSERVATIONSf 



H. COTTIEKt, B. KOOS 



Institute of Pathology, University of Bern, Switzerland 



AND S. BARANDUN 



Medical Department, Tiefenauspital, Bern, Switzerland 



SUMMARY 



Lymphatic, bone-marrow and liver tissues of adult mice and rats given short term 

 whole-body X-irradiation with 600, 700 and 1,000 r were examined by electron micro- 

 scopy at early intervals after exposure. The first detectable changes appeared in the 

 nuclei of radiosensitive cells (chromatin derangement with focal condensation, margina- 

 tion and oedema) at approximately 15 mmutes post-irradiation. Apparent membrane 

 fading (real or due to tangential sectioning) was more often seen in irradiated than in 

 non-irradiated cells, but no precise evaluation of this finding is possible without serial 

 sectioning. No morphologic evidence is found for intracentriolar damage as the cause of 

 radiation-induced mitotic delay. 



It is conceivable that electron microscopic studies of the ultra-structure of 

 cells following irradiation may provide some clue as to the vulnerable 

 element(s) which are important for altered function and/or ceU death. Such 

 observations, if possible, may well contribute to a better understanding of the 

 nature of the basic and initial effects of radiation upon the cell at a chemical 

 level. However physiological variations and artifacts of normal tissue being 

 studied by electron microscopy are still insufficiently known to permit a 

 precise characterization of radiation-induced early and discrete abnormalities. 

 Accordingly the observations to be presented must be interpreted with 

 caution. Some ultrastructural changes in irradiated cells have already been 

 described; but most of these reports deal with cell types that do not undergo 

 early death after exposure to radiation doses such as used in our studies (rat 

 liver cells — Glauser, 1956; mouse Paneth cells — Hampton and Quastler, 1958; 

 Paramecium, Schneider, 1961). 



This preliminary report will include electron microscopic observations 

 made on components of highly sensitive as well as more resistant cells from 



t Research supported by the Swiss National Foundation for Scientific Research (Com- 

 mission for Atomic Science). 



X Present address: Brookhaven National Laboratory, Medical Research Center, Upton, 

 L.I., N.Y. 



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