SECTION TWO 



ORCEIN - PICRO FUCHSIN (Van Gieson) 

 For elastic and collagen fibres 



Solutions required: 



A. Orcein (Unna) i% in 80% alcohol 100 ml. 

 Hydrochloric acid, cone. . . i ml. 



B. Picro-fuchsin (Van Gieson). 



Technique: 



1. Sections are mounted on slides and brought down to 70% 

 alcohol in the usual manner. If tissues have been fixed in a fluid 

 containing mercury, the mercurial precipitate is removed by the 

 standard technique. 



2. Immerse in orcein solution (formula as above) for half an 

 hour or longer if necessary ; then rinse in acid alcohol. 



3. Rinse in 70% alcohol; then in water. 



4. Stain with picro fuchsin (Van Gieson) for three to five min- 

 utes. 



5. Rinse rapidly (not more than a few seconds) in water. 



6. Dehydrate rapidly; clear, then mount. 



Results: 



Collagen fibres are stained red ; elastic fibres, brown ; erythro- 

 cytes, epithelia, muscle, etc., yellow. 



OSMIC Acm 



A rapid technique for staining fat in frozen sections 



Solutions required: 



A. Osmic acid 1% aqueous. 



Note: Store in an amber bottle. 



B. Eosin, yellowish, 1% aqueous. 



Technique: 



I. Tissues are fixed as follows : 



Place 22 5 ml. distilled water in a 50-ml. beaker and heat to 

 about 90° C; then add 2-5 ml. formalin; raise to boiling point; 



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