MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



4. Fix sections alternatively to slides marked A, B and C. 



5. Remove paraffin wax with toluol, and pass through the usual 

 descending grades of alcohol to distilled water. 



6. Stain slide A immediately with the methyl green-pyronin 

 for twenty minutes. 



7. Meanwhile place slide B in distilled water, adjusted to pH 

 6-0 in the oven and leave there for an hour at 37° C. 



8. Place slide C in the ribonuclease solution in the oven at 

 37° C. and leave there for an hour. 



9. Meanwhile take slide A, after it has been in the methyl 

 green-pyronin for twenty minutes, and wash it rapidly with dis- 

 tilled water. 



10. Slide A is then differentiated with 95% alcohol for five to 

 ten minutes. 



11. Dehydrate slide A with absolute alcohol; then wash with 

 toluol and mount in balsam or D.P.X. or Cristalite. 



12. When slide B has been in the oven for an hour, stain it with 

 the methyl green-pyronin, differentiate, dehydrate and mount 

 exactly as in the case of slide A. 



13. When slide C has been in the oven for an hour, stain, 

 differentiate, dehydrate and mount exactly as slides A and B. 



14. Examine and compare specimen C with A and B. 



Notes : 



(a) Methyl green is unique in that it will stain some, but not 

 all basophilic substances. It will stain high-polymer DNA as it 

 occurs in the nuclei, but it will not stain depolymerized DNA or 

 RNA in any form. In specimen B (above) it will be found that 

 although the methyl green staining may have been completely 

 abolished, Feulgen's reaction remains unchanged. Interesting 

 comparisons can be made between sets of slides as B and C (above) 

 with sections from the pancreas, kidney, lung, liver, genital glands, 

 skin, etc. (See Professor J. Brachet's original 1942 paper*). 



{h) It may be found necessary, depending upon the fixative 

 used and the organ to be studied, to raise the concentration of the 

 ribonuclease solution to as much as o-6% to obtain optimum 

 results. 



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