AUTORADIOGRAPHY 



339 



Disadvantages. There are possibilities of radioisotope loss during the 

 wet processing. The sensitivity is relatively low, and the base emulsion 

 may interfere with staining and tend to reduce the resolution. 



Recommended Usage. The stripping-film method has proved satisfac- 

 tory for cytological studies with both plant and animal tissues. Quan- 

 titative results at low levels of activity have been made possible by the 

 counting of grains. 



Typical Method. The stripping-film techniciue was described by Pelc 

 (32), and the following is the procedure, as later described by Doniach 



^Z\= Emulsion 



Emulsion 

 Gelatin 



Gelatin^ ^Emulsion 



Fig. 7-4. Stripping-film method. The fihii i.s cut, as at (a); removed, as in (6); 

 inverted and floated on water, as shown at (c) ; and picked up on the moimted speci- 

 men, as shown at (d). The fihn is draped around the slide to make a tight fit, as in 

 (e). [Courtesy of Patrick J. Fitzgerald, Eva Simmel, Jerry Weinstein, and Cynthia 

 Martin, Radioautography: Theory, Technic, and Applications, Lab. Invest., 2: 181-222 

 (1953), Paul B. Hoeber, Inc., publisher.] 



and Pelc (18) [Fig. 7-4 is a schematic representation from Fitzgerald et al. 



(10)]: 



1. The fresh tissue is placed in absolute alcohol for 8 to 15 hr, then con- 

 secutively in fresh absolute alcohol for 1 hr, in benzene for 15 min, and in 

 warm benzene for 15 min; embedded in paraffin; sectioned; and floated 

 on warm water. 



2. The sections are picked up on slides that have been previously 

 "subbed"' (dipped in an aqueous solution of 1 per cent gelatin and 0.1 per 

 cent chrome alum and dried) . The slide and section are drained, blotted, 

 and dried on a hot plate. 



3. The preparation is dewaxed with xylene, followed by alcohol and 

 thorough washing in water. 



