MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



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 lo// 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. 



5. Counterstain in Solution B for one minute. 



6. Wash quickly in tap water ; transfer sections to slides ; drain 

 and mount in glycerine jelly, previously melted in an oven or on a 

 water bath. 



Results: 



Fat globules, black or greyish black against a red background. 

 Caution : Osmic acid vapour is injurious to the eyes. 



PASINI'S STAIN (Improved) 

 For dififerentiation of connective tissue 



Solutions required: 



A. Iron alum 2-5% aqueous. 



B. PasinVs stain: 



Unna's aniline blue-orcein . . 10 ml. 



Eosin bluish 2% in 50% alcohol . . 12 ml. 



Acid fuchsin . . . . . . 0-3 gm. 



Neutral glycerine . . . . • • 5 ml- 



Technique: 



1. Tissues should be fixed in Heidenhain's susa mixture and 

 embedded in L.V.N. Sections are cut 3/^ in thickness. 



After removal of mercuric precipitate in the usual manner sec- 

 tions are mordanted in Solution A for twenty-four hours. 



2. Transfer to Solution B for three to ten minutes. 



3. Transfer to 95% alcohol and agitate for about one minute or 

 until the colour ceases to come out in clouds. 



4. Immerse in absolute alcohol for one minute ; then blot, clear 

 and mount. 



180 



