MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



Technique: 



1. Air-dried smears are fixed by flaming in the usual manner. 



2. Immerse in the methylene blue solution for five minutes. 



3. Pour off excess stain and carefully wash the preparation in 

 running water. 



4. Drain off excess water; then cover the preparation with 

 safranin solution and allow the stain to act for one to two minutes. 



5. Rinse well with distilled water; drain; blot dry; examine. 



Results: 



The polar bodies appear deep blue, while the bacterial cells are 

 distinctly red. 



NEW FUCHSIN - CONGO RED 

 For bacterial cell walls, particularly E, Coli and B. Cereus 



Solutions required: 



A. New fuchsin 1% aqueous. 



B. Congo Red . . . . . . . . i gm. 



Buffer solution pH 9-5. . . . . 100 ml. 



Warm to dissolve 



Technique: 



1. Smears of the organisms are made on slides in the usual 

 manner, with a wire loop, i mm. diameter. 



2. Allow the smears to dry in the air without the use of heat. 



3. Stain in the new fuchsin solution for three to four minutes. 



4. Pour off excess stain: then rinse the slides gently until the 

 colour ceases to come out. 



5. Shake off excess water and set the slide aside to dry in the 

 air. 



6. Place the air dried slides on a warm plate at 50° C. for ten 

 to twenty seconds. 



7. Remove from the hot plate and using a wire loop i mm. in 

 diameter, add a loopful of the congo red solution and spread this 



386 



