MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



3. Differentiate in 2% acetic acid, 



4. Rinse in distilled water; mount in Farrant. 



Results: 



Free fatty acids, blue. Neutral fats, red. 



NILE BLUE - PICRO FUCHSIN (Murray-Drew) 

 For bacteria and actinomyces in pathological tissues 



Solutions required: 



A. Picro fuchsin (Van Gieson). 



B. Nile Blue sulphate aqueous 1%. 



Technique: 



1. Formalin-fixed material is embedded in paraffin wax, or 

 frozen sections may be employed. 



2. Take sections down to distilled water in the usual manner 

 then stain in picro fuchsin for two or three minutes. 



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. 



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