STAINING, PRACTICAL AND THEORETICAL 



6. Rinse in 70% alcohol. 



7. Stain in solution B for six hours. 



8. Rinse in 70% alcohol. 



9. Wash in running tap water for five to ten minutes. 



10. Rinse in distilled water. 



Note: If desired, a counterstain may be applied at this stage. 



11. Rinse in 95% alcohol for thirty seconds. 



12. Immerse in absolute alcohol for thirty seconds. 



13. Clear in two changes of xylol and mount in Clearmount, 

 Cristalite or D.P.X. 



Results: 



The beta cells in the pancreatic islets of man, dog, frog, guinea 

 pig, rabbit and mouse are stained purple. 



Notes: 



(a) It was found that the staining of any species that had been 

 fixed in Zenker's or Helly's fluids was capricious, and no staining 

 was observed in tissues fixed in fluids containing alcohol. The 

 beta granules are known to be alcohol soluble. 



(b) The authors state that as opposed to the argentaffin granules 

 of carcinoid tumours of the intestine, the beta granules in islet 

 tumours are not readily demonstrable. Most of the techniques 

 used to stain beta cells in non-neoplastic islets do not colour a 

 significant number of cells in tumours arising from pancreatic 

 islets. Moreover, the unstained cells will not accept the counter- 

 stains commonly used in such techniques and appear as alpha 

 cells. 



(c) It is stated that many types of counterstains can be used 

 including Van Gieson, light green-orange (Halmi, 1952), phloxine 

 (Fisher & Haskell, 1954), Gomori's trichrome (Gomori, 19506), 

 iron haematoxylin-metanil yellow, light green, fast green FCF, 

 etc. 



(d) The authors state that Gomori's (1950a) technique failed to 

 stain the beta granules consistently in non-neoplastic islets and did 

 not stain any of the beta cells in islet tumours, and the introduction 



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