AUTORADIOGRAPHY 



case the ruthenium was administered in an 

 insokible particulate form. 



Ru^°^ particles were administered to mice 

 by intravenous and intratracheal injection 

 in 0.1 % aqueous dispersions of the wetting 

 agent, Tween 80 (6). The animals were sacri- 

 ficed after 100 to 420 days exposure to beta 

 radiation. One experiment in autoradio- 

 graphic quantitation was conducted on a 

 single mouse into which 47 /xc of Ru^"® par- 

 ticles, ranging in size from 0.5 to 0.8 micron, 

 were injected into the tail vein of the mouse. 

 A portion of these particles lodged in the 

 lungs of the animal. The lungs were excised 

 after 100 days exposure and fixed in 70% 

 ethyl alcohol. Autoradiographic processing 

 was standard, as outlined above. The re- 

 sult was a series of sections through the 

 entire lung; one section was stained with 

 orcein, one unstained autoradiogram fol- 



» t-IOOft-) 



Fig. 5. Autoradiogram of sheep thyroid four 

 hours following administration of 100 nc of I'^^ 

 Hematoxylin and eosin stain. Specific increase in 

 grain density over various colloidal areas indicates 

 variable uptake by the follicles. 



It is important that the investigator be 

 aware of the type of response to be expected 

 after processing certain types of tissue and 

 report the appearance of representative au- 

 toradiograms that are taken to illustrate the 

 uptake of the radioisotope at selected times 

 following administration. Specifically, the 

 autoradiographic response in the thyroids of 

 the experimental animals mentioned is that 

 of single grains diffusely covering specified 

 areas of the thyroid. Other types of emul- 

 sions will register the location of I^^^ as 

 tracks rather than diffuse grains. Changes 

 in the development procedures are necessary 

 to register the I^^^ as tracks rather than 

 grains. 



It is interesting to compare at this point 

 the autoradiographic response of Ru^"®, an- 

 other beta emitter having some gamma 

 emission, and a half-life of one year. In this 



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V 



^^ % 





**' ^ * 



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• " " " ■ 



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J * 





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50/X- 





.-^^ 



:# 





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Fig. 6. Autoradiogram of sheep thyroid 129 

 days following administration of 5 /xc of I"' per 

 day. Negative grain density is apparent over areas 

 of edema, with a limited uptake in the colloidal 

 areas of the microfollicles. 



4 



