STAINING, PRACTICAL AND THEORETICAL 



formation of a blackish blue or brownish compound that will be 

 taken up by the tissue to obscure the picture. Gatenby & Beams 

 (1950, p. 69) state that in recent years the use of aniline oil for 

 clearing delicate tissues (e.g. mammalian testicular material) has 

 become widespread because the higher alcohols can be avoided. 

 The same authors state that dehydration is started with 50% or 

 70% alcohol, and that the alcohol is gradually replaced with 

 aniline oil. 



Aniline oil should be stored in tightly closed dark bottles, as it 

 will absorb water from the atmosphere and darken in colour. 



BUTYL ALCOHOL TERTIARY 



For dehydrating and clearing tissues, for paraffin embedding, in 

 place of ethyl alcohol and xylol. The reagent is miscible with 

 water and with paraffin wax, and causes less shrinkage and harden- 

 ing of tissue than does ethyl alcohol and xylol. It is also a useful 

 substitute for ethyl alcohol for dehydrating material stained with 

 methylene blue and other dyes which are easily extracted by ethyl 

 alcohol. 



Technique: 



After fixing and washing tissues in the usual manner pass into : 



1. Tertiary butyl alcohol (T.B.A.) 50% aqueous for 1-2 hours. 



2. 70% Aqueous T.B.A. 2 hours to several days. 



3. 85% Aqueous T.B.A. for 1-2 hours. 



4. 95% Aqueous T.B.A. for 1-3 hours. 



5. Pure T.B.A. for 3 changes of 4 hours in each. 



6. Equal parts of liquid paraffin and T.B.A. for 1-2 hours. 



7. Infiltrate in paraffin wax. 



CAJEPUT OIL 



For clearing 



This reagent will absorb small amounts of water without cloud- 

 ing, and it is, therefore, particularly useful in wet climates as a 

 clearing agent in place of xylol. Cajeput oil is considerably more 

 expensive than xylol, however. 



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