SECTION TWO 



Notes: 



(a) See Threadgold's Sudan black method also. 



(b) The osmic acid technique demonstrates the development of 

 secretory granules, but it does not show cellular detail and all 

 stages of cytomorphosis of the interstitial cell as clearly as the 

 Sudan black method. 



{c) Interstitial cells, actively synthesizing secretion droplets, are 

 revealed by the presence of black lipid droplets of various sizes, 

 in the cytoplasm; readers should consult the original paper for 

 more detailed information and photomicrographs. 



(d) Steps 3 and 4 may be omitted, but counterstaining will 

 then be necessary to reveal cellular detail. 



{e) Counterstaining with Ehrlich's haematoxylin or with eosin 

 in 30% alcohol may be tried, but both stains tend to obscure 

 the results, although the eosin is stated to give a fair contrast. 



Reference: Threadgold, L. T. (iQS?)- 



OSMIC ACID 

 A rapid technique for staining fat in frozen sections 



Solutions required: 



A. Osmic acid 1% aqueous. 



Note: Store in an amber bottle. 



B. Eosin, yellowish, 1% aqueous. 



Technique: 



1 . Tissues are fixed as follows : 



Place 22-5 ml. distilled water in a 50-ml. beaker and heat to 

 about 90° C; then add 2-5 ml. formalin; raise to boiling point; 

 drop in a thin piece of the tissue ; then place the beaker in an oven 

 at 60 to 65° C. for ten minutes. 



2. Cut frozen sections 10/.1 thick, and place them in another 

 50-ml. beaker. 



3 . Boil Solution A in a large test-tube and pour onto the sections, 

 then transfer to an oven at 60° C. for five minutes. 



4. Wash sections in a dish of cold tap water after pouring back 

 the osmic acid, which may be used again, into the stock bottle. 



337 



