STAINING, PRACTICAL AND THEORETICAL 



4. Immerse in a fresh lot of pyridine for twenty-four hours at 

 60° C. 



5. Wash in running water for two hours. 



6. Immerse in solution B for one hour at 60° C. 



7. Wash in distilled water. 



8. Rinse in 70% alcohol. 



9. Stain in the Sudan black solution for fifteen minutes. 



10. Rinse in propylene glycol. 



11. Mount in Aquamount or in glycerine jelly. 



12. Take frozen sections from the same tissue block, omit 

 stages 3 and 4, and proceed as at stages 5 to 1 1 above. 



13. Compare the pyridine extracted sections with the unex- 

 tracted sections. 



Results: 



Structures that are stained with Sudan black in the unextracted 

 sections are confirmed as lipid-containing if they are unstained in 

 the pyridine-extracted specimens. 



Reference: Baker, J. R. (1946). 



SUDAN BLUE 

 For demonstrating degenerated myelin 



Solution required: 



Sudan blue, saturated in 50% 

 alcohol or ethylene glycol 



Technique: 



1. Tissues should be fixed for at least three days in 10% neutral 

 formalin. 



2. Frozen sections are soaked one minute in 50% alcohol; then 

 one minute in 70% alcohol ; then stained from fifteen minutes to 

 several hours in a saturated solution of Sudan blue in 50% alcohol. 



3. Rinse for a few minutes in 50% alcohol; then in distilled 

 water. 



432 



