MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



7. Clear by transferring to solutions of 25%, 50% and 75% 

 methyl salicylate in cellosolve for twenty-four hours in each. 



8. Store in methyl salicylate. 



Note: If glycerin is used for clearing the technique has to be 

 modified as follows : 



Omit stage 6 and transfer directly from the Alizarin Red S 

 solution into a series of 50%, 70% and 80% glycerin for twenty- 

 four hours in each ; then store in pure glycerin. 



Results: 



Soft tissues: transparent. Osseous tissue: deep blue. Carti- 

 lage : dark blue. 



Note: The relative degree of ossification and chondrogenesis 

 which has taken place is indicated by the intensity of the stains. 

 Bone and cartilage may be stained separately by omitting stage 2, 

 or stage 5 for cartilage. 



For foetal specimens 



The technique is particularly suitable for mammalian embryos, 

 for demonstrating minute bones and foetal ossification. 



Solutions: 



A. Alizarin Red, S, 1% aqueous 



(freshly prepared) . . . . i litre 



Potass, hydroxide 1% aqueous . . i ml. 



B. Potass, hydroxide . . . . 10 gm. 



Water . . . . . . . . 800 ml. 



Glycerin . . . . . . . . 200 ml. 



Note: For small specimens 5 gm. potass, hydrox- 

 ide is sufficient. 



Technique: 



Fix in 95% alcohol for at least two weeks after making a midline 

 abdominal incision to allow penetration of the fixative. 



1. Rinse in tap water. 



2. Immerse for at least four weeks in 1% potass, carbonate. 



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