Rapid Staining Methods 67 



Staining 



Nitrocellulose-mounted sections are transferred from the 70% alco- 

 hol to Avater and then into any desired stain. After staining they prob- 

 ably will require special care. If after dehydration the sections are 

 placed in absolute ethyl alcohol and show a tendency to fall off, because 

 the nitrocellulose dissolves, follow the 95% alcohol with isopropyl alco- 

 hol, 2 changes, and then xylene. Another method is to follow the 95% 

 alcohol with carbol-xylol (page 410), several changes, until the sections 

 look clear. Fogginess or colored droplets on the slides indicate traces of 

 water. If carbol-xylol is used, rinse it off by dipping the slide for 2-3 sec- 

 onds in xylene. Carbol-xylol must be removed; any of it left in the sec- 

 tions will fade stains in a short time, almost overnight. Warning: keep 

 fingers out of carbol-xylol; it contains carbolic acid. Wash it off immedi- 

 ately if any spills on the skin and use Lanolin for skin irritation. 



Irregular staining usually is caused by an uneven coat of nitrocellu- 

 lose; this can be prevented by tilting the slide immediately after the 

 solution is applied. If the nitrocellulose is thicker than 1% uneven 

 staining may result. A colored background indicates a thick coat of 

 nitrocellulose. Sometimes irregular staining is due to loosening of parts 

 of the section. 



Rapid Staining Methods 



Pinacyanole Method (Proescher, 1933; Humason and Lushbaugh, 

 1961) 



Staining and mounting time, 30-90 seconds 



1. Mount frozen section (fresh or fixed) on slide; drain off excess water. 



2. Cover section with several drops of stain: 3-5 seconds, 

 (pinacyanole, 0.5% in either 70% methyl or ethyl alcohol; keep stock 

 solution in refrigerator.) 



3. Float section off into tap or distilled water: 5-10 seconds or until free 

 of excess stain (longer washing will not alter intensity). 



4. Remount on clean side, blot excess Avater from around section, cover 

 with Aquamount,^ glycerine or glycerine jelly, and cover glass. 



^ Edward Gurr, London. 



