ALTORADIOGRAPHY OF TISSUE 



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Fig. 10. Autoradiogram of rat ovary 24 hours 

 after administration of 2.5 juc of P'^ pgj. gram of rat. 

 Concentrations of P^^ appear over cellular ele- 

 ments lining the follicular cavity, surrounding the 

 ova and in some corpora lutea. {Courtesy J . Biol. 

 Phot. Assoc.^^). 



tion of P^2_ ^n increased grain density is 

 noticeable in the area of three developing 

 ova. The autoradiogram may be compared 

 with the adjacent hematoxylin and eosin 

 stained section in Figure 11. 



In direct contrast with this gross survey 

 method for the localization of P^- is the ex- 

 treme detail and precise localization ob- 

 tained by Guidotti (9). Guidotti mounted 

 paraffin sections, 2 to 4 ;u thick, which were 

 stained, dehydrated, and allowed to air dry. 

 These were given a thin coating of 1 % "Plexi- 

 glas" solution in chloroform. The chloroform 

 was allowed to evaporate completely in a 

 dry atmosphere. An emulsion having a dried 

 thickness of 100 to 150 microns, was pre- 

 pared from Ilford G-5 type emulsion in gel 

 form and glued to the section by means of a 

 15 % solution of shellac in absolute alcohol. 



The surface of the emulsion was then cleaned 

 with absolute ethyl alcohol, to remove the 

 impermeable layer. This method allows the 

 fixing and staining of the tissues by means 

 of all of the reagents commonly employed 

 in histology, without any damage to the 

 emulsion. The exposure of the tissue was for 

 24 hours at 2°C. The emulsions were proc- 

 essed by the Temperature Development 

 Method. Good adhesion and minimum sep- 

 aration between specimen and emulsion are 

 obtained, thus permitting reliable extrapo- 

 lation of the electron tracks from P^-. 



The Temperature Development Method 

 of Dilworth, Occhialini and Payne, 1948, and 

 Dilworth, Occhialini and Vermaesen, 1950, 

 as modified by Guidotti, is worthy of specific 

 mention. Essentially it consists of soaking 

 the slides in distilled water for 30 to 40 min- 

 utes, beginning at room temperature, and 



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Fig. 11. Stained histological section adjacent 

 to Fig. 10 of rat ovary 24 hours after administra- 

 tion of 2.5 Aic of P'2 per gram of rat. Three develop- 

 ing ova are seen in central portion. (Courtesy J. 

 Biol. Phot. Assoc.'^). 



