SECTION TWO 



2. Decalcify in solution C. 



3. Wash in water for twenty-four to forty-eight hours. 



4. Immerse in 10% formalin for three to five days. 



5. Cut frozen sections at 10 to 15/n and drop them into dis- 

 tilled water. 



6. Immerse in the orcein solution for seven days. 



7. Immerse the sections in 95% alcohol for two to twenty- four 

 hours or until a satisfactory degree of differentiation has been 

 obtained, which is determined by microscopic examination at 

 intervals. 



8. Immerse the sections in distilled water for about an hour. 



9. Dehydrate and clear. 



10. Mount in Canada balsam in xylol or in Exemel or D.P.X. 



Results: 



Myelin sheaths appear reddish brown in the dental pulp. Fibres 

 emerging from Raschkow's plexus can be followed almost to the 

 odontoblast layer, while Schmidt-Lantermann incisures, infundi- 

 bular spaces and axons remain relatively unstained. 



Note: 



The author (Fuentes) states that his results appear to suggest 

 that orcein can be used in a manner similar to that described 

 above as a selective stain for myelin sheaths, and that trials made 

 with sciatic nerve, spinal dorsal roots and cord in adult rabbit 

 have yielded similar results. 



Reference: Fuentes, A. (i960). 



ORCEIN - METHYLENE BLUE 

 For elastic fibres and connective tissue 



Solutions required: 



A. Orcein {Unna-Taenzer) 

 Orcein . . . . . . . . i gm. 



70% alcohol . . . . . . 100 ml. 



Heat on a water bath to dissolve; cool; filter; 

 then add: 

 Hydrochloric acid, cone. . . i ml. 



Shake well. 



329 



