STAINING, PRACTICAL AND THEORETICAL 



3. Wash with distilled water. 



4. Stain in Nile Blue sulphate for four to twenty-four hours. 



5. Rinse in distilled water until the washings are tinted pale 

 blue. 



6. Drain off excess water; then blot the preparation carefully 

 but thoroughly. 



7. Dehydrate rapidly in absolute alcohol ; then clear in xylol. 



8. Differentiate in clove oil for five to fifteen minutes (for para- 

 ffin sections) or for several hours in the case of thick frozen sections. 



9. Rinse in two or three changes of xylol to remove clove oil; 

 then mount. 



Results: 



Bacteria and chromatin are stained blue; collagen fibres, red; 

 mast cell granules, blue-black; fibrin, blue or reddish orange; 

 erythrocytes and keratin, yellow. 



Reference: Drew & Murray (19 19). 



NINHYDRIN 

 For amino groups 



Solutions required: 



A. Celloidin 0-5% in equal volumes of absolute alcohol and 

 ether 



B. Ninhydrin (triketohydrindene hydrate), 0-5% aqueous 



Technique : 



1. Fix pieces of fresh material in 10% formalin for two to 

 four hours. 



2. Wash in water and cut frozen sections. 



3. Wash in 70% alcohol, followed by 90% and absolute alcohol. 



4. Coat sections on slides with the celloidin solution, then 

 allow the solvent to evaporate for a few minutes. 



5. Immerse sections in solution B (Ninhydrin) for one minute 

 at 90° C. 



326 



