MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



D. Gram's iodine. 



E. Aniline oil. . . . . . i volume 



Xylol . . . . . . . . I volume 



Technique: 



1 . Pieces of tissue should be fixed in Zenker's fluid, washed in 

 running water, dehydrated, cleared and embedded in paraffin wax 

 in the usual manner. 



2. Fix thin sections to slides, de-wax, and treat for the removal 

 of mercuric precipitate by the standard technique. 



3. Stain in the fuchsin solution for ten to thirty minutes. 



4. Differentiate in formalin until the bright red colour is re- 

 duced to pink. 



5. Wash in distilled water. 



6. Counterstain in the picric acid solution for a few minutes 

 until the preparation assumes a purplish yellow colour. 



7. Wash in distilled water. 



8. Differentiate in 95% alcohol until the sections are red again, 

 and yellow and red coloration begins to come out. 



9. Rinse in distilled water. 



10. Stain in aniline gentian violet for five to ten minutes. 



1 1 . Rinse in distilled water. 



12. Stain in Gram's iodine solution for one minute. 



13. Drain and blot dry. 



14. Differentiate with aniline-xylol until colour ceases to come 

 out of the sections. 



15. Clear with two changes of xylol and mount. 



Results: 



Gram-positive organisms are stained blue, while Gram- 

 negative are red. Tissue, red and blue ; fibrin, deep blue. 



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