STAINING, PRACTICAL AND THEORETICAL 



Technique: 



1. Fix small pieces of tissue in reagent A for twenty-four to 

 forty-eight hours. 



2. Transfer to a porcelain plate or a watch glass and leave 

 exposed to the air until the alcohol has evaporated. 



3. Embed in reagent B. 



4. Cut sections at 6 to lO/x and mount them on slides. 



5. Without removing the wax from the sections on the slides, 

 immerse them in reagent C for fifteen to forty-five minutes. 



6. Rinse rapidly in reagent D. 



7. Dewax the sections with benzene, and clear in benzene. 



8. Mount in paraffin liquid. 



Results: 



Cholesterol assumes a brown colour, but its esters are un- 

 coloured. 



The preparations are stable for some considerable time. 



Note: 



If the colour is not considered strong enough, it may be 

 intensified as follows: 



From stage 6 above, proceed as follows: 



[a) Wash in a mixture consisting of i volume of absolute 

 alcohol and 3 volumes of nitric acid, cone, to remove excess 

 bismuth. 



{b) Wash rapidly in absolute alcohol. 



[c) Immerse in a dilute solution of ammonium sulphide for a 

 few seconds. 



{d) Wash in absolute alcohol. 



[e) Clear in benzene or xylol. 



(/) Examine in paraffin liquid or mount in D.P.X. (Lendrum & 

 Kirkpatrick). 



References : 



Brunswik, H. (1922). 

 Lison, L. (1936). 



186 



