SECTION TWO 



Note: This treatment with iodine is recommended for all 

 tissues, whether they have been fixed in mercurial fixatives or not, 

 as it often shortens the staining time necessary and makes the 

 shade deeper. 



6. Wash well with water. 



7. Immerse in solution B for about one half to two minutes 

 until the natural colour of the section has been restored. 



8. Wash well with water. 



9. Stain for five minutes to two hours in a coplin jar filled with 

 solution C. 



Note: Elastic fibres, five to ten minutes. Beta cells, fifteen to 

 thirty minutes, or longer. Pituitary, thirty minutes to two hours. 



10. At intervals examine the slide, after rinsing with 90% 

 alcohol, under the microscope to ascertain the depth of staining, 

 but taking care that the preparation is not allowed to dry. If the 

 desired depth of staining has not been attained, the slide may be 

 returned to the stain and rinsed with alcohol again before further 

 examination: this process may be repeated any number of times 

 until the desired degree of staining has been reached. 



1 1 . If desired a counterstain may now be applied : haematoxylin 

 - Orange G is best for most purposes, but for pancreas and pitui- 

 tary, a trichrome stain of the Masson type or the Mallory- 

 Heidenhain technique can be used to bring out all types of cells. 

 In either case. Light Green or Fast Green, FCF should be used 

 in place of the aniline blue as their shades contrast better with the 

 purple of the aldehyde fuchsin. 



12. Dehydrate with absolute alcohol; clear in xylol and mount. 



Results: 



The following are stained deep purple : 



(I) Elastic fibres of all tissues, whatever fixative has been 

 used. 



(II) Mast cells, after any fixative. 



(Ill) The chief cells of the gastric mucosa, particularly well 

 stained after fixation in formalin or Bouin. 



49 



