MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



FONTANA STAIN 

 For argentaffine granules 



Solutions required: 



A. Silver oxide (Fontana). 



B. Sodium thiosulphate 5% aqueous. 



Technique: 



1. Tissues are fixed in 10% neutral formalin, washed, dehy- 

 drated in alcohol, cleared in cedarwood oil, and embedded in 

 paraffin wax as usual. 



2. Fix sections to slides, bring down to distilled water and wash 

 thoroughly in two or three changes of neutral, freshly distilled 

 water. 



3. Immerse in the silver oxide (Fontana) solution for twelve 

 to twenty-four hours in the dark in a covered, scrupulously clean 

 vessel. 



4. Wash in neutral, freshly distilled water for one minute. 



5. Immerse for one minute in the sodium thiosulphate. 



6. Immerse in tap water for ten minutes. 



7. Counterstain, if desired in carmalum. 



8. Dehydrate; clear in xylol and mount. 



Results: 



Argentaffine granules, black. 



FONTANA STAIN - SILVER NITRATE 

 For reticular and collagen fibres 



Solutions required: 



A. Strong ammonia solution (sp. gr. 



o-88o) . . . . . . . . 10 ml. 



Distilled water . . . . . . 90 ml. 



B. Potassium permanganate 0-5% aqueous. 



C. Oxalic acid 1-5%. 



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