SECTION TWO 



Technique: 



1. Fix in 10% formalin for one to three days. 



2. Dehydrate, clear and embed in paraffin wax as usual. 



3. Cut sections as usual but do not mount them on slides. 



4. Arrange a series of watch glasses containing xylol, the usual 

 graded alcohols and distilled water in the order in which they are 

 to be used for dewaxing and hydrating the sections. 



5. Arrange a series of watch glasses containing the reagents in 

 the order in which they will be used in the following technique. 



6. Dewax and hydrate the sections by successively placing them 

 in the watch glasses containing xylol, alcohols and water, handling 

 the sections throughout as in the case of frozen sections. 



7. Immerse in 1% potassium permanganate (solution A) for 

 fifteen seconds to one minute. 



Note: If the tissue has been fixed for a long time or if it contains 

 a considerable quantity of blood, or if it is very cellular, the time 

 in the potassium permanganate solution can be extended over one 

 minute, sometimes as long as ten minutes, until a good impreg- 

 nation of the connective tissue fibres is effected, but in such cases 

 the staining of the cells might be suppressed. 



8. Wash in distilled water for five to ten seconds. 



9. Decolorize in 5% oxalic acid or 2% potassium metabi- 

 sulphite for about ten to twenty seconds, until the brown colour 

 disappears completely. 



ID. Immerse in a fresh lot of distilled water for one minute. 



11. Immerse in 2% iron alum (solution C) for one minute. 



12. Transfer to a fresh lot of distilled water. 



13. Impregnate in Gomori's methenamine silver (solution F) for 

 about two minutes. 



14. Wash in solution G for about fifteen seconds. 



15. Reduce in solution H for one minute. 



16. Repeat steps 12 to 15 several times until the reticulum and 

 collagenous fibres are completely stained, as the first staining is 

 usually insufficient. 



Note: If it is desired to stain the cells also, then the following 

 procedure should be followed. 



17. After the first insufficient staining of the reticulum and 

 collagenous fibres, the sections are rinsed in distilled water. 



411 



