MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



Technique: 



1. When Solution B begins to boil, add 62 ml. of Solution A 

 slowly, in small portions at a time over a period of five minutes, 

 with constant stirring. 



2. Continue with the boiling and stirring for a further period of 

 two or three minutes until a coarse precipitate is obtained. 



3. After cooling filter by means of a Buchner funnel and flask 

 attached to a suction pump. 



4. Wash the precipitate with distilled water until the runnings 

 are colourless and the filtrate a clear azure blue; this usually 

 requires 8 to 10 litres distilled water. 



5. The preparation is then dried overnight in an incubator, 

 after removing the filter paper. 



Preparation of the staining solution : 



1. The dried elastin stain is now dissolved in 550 ml. absolute 

 alcohol plus I ml. HCl in a i -litre flask, the neck of which is 

 plugged lightly with cotton-wool. Solution is effected by boiling 

 gently for about thirty minutes on a water bath or electric hot- 

 plate. 



2. Cool; filter; add 19 ml. concentrated HCl; then shake well 

 and allow to stand for at least twenty-four hours. 



Staining technique: 



1. Sections are brought down to distilled water; then treated 

 with 0'5% aqueous potass, permanganate for five minutes. 



2. Rinse and bleach with 5% aqueous oxalic acid; then wash in 

 running water. 



3. Transfer to elastin stain for at least two hours at 37° C. or 

 for one half to one hour in an oven at 60° C. 



4. Blot and treat with absolute alcohol for three to five minutes. 



5. Rinse with water and counterstain for three minutes with 

 neutral red (Jensen). 



6. Rinse and differentiate the neutral red for a few seconds in 

 absolute alcohol. 



7. Rinse in distilled water, then pour on 0-5% picric acid 

 aqueous and wash off immediately with running water. 



222 



