MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



3. By means of a camel-hair brush, moistened with 50% alcohol, 

 transfer sections from the microtome knife directly to the first of a 

 series of dishes previously arranged as follows, in order of their 

 use : 70% alcohol, Sudan Black solution (as above), 50% alcohol ; 

 distilled water. 



4. After immersion in 70% alcohol (in the first dish) for two 

 minutes, stain in the Sudan Black for ten minutes, or longer if 

 time permits. 



5. Rinse in the 50% alcohol. 



6. Transfer to the distilled water : mount in Apathy's medium, 

 or, if there is sufficient time, counterstain for about three minutes 

 in Carmalum; then rinse in distilled water before mounting. 



Results: 



Neutral fat and myelin : blue-black to black; nuclei: red. 



GELATINE EMBEDDING 



This method of embedding is employed when sections of loose 

 friable tissues are required. Dehydration is entirely eliminated 

 since the embedding takes place directly from water. The gela- 

 tine which is retained during the staining processes holds the 

 tissues together without absorbing the stain itself. 



Solution required: 



A. Gelatine 5% 



Gelatine . . . . . . • • 5 gi^« 



Phenol I % aqueous . . • • 95 ^* 



Warm in an oven to about 45° C. then stir until 

 the gelatine has dissolved; raise to about 60° C. 

 before filtering through fine calico. 



B. Gelatine 10% 



Phenol I % aqueous . . . . 90 ml. 



Gelatine . . . . . . . . 10 gip. 



Prepare exactly as for Solution A. 



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