Staining Paraffin Sections 57 



Stain Formulas 



The existence of several exhaustive formularies makes unncessary 

 the compilation of an extensive list of stain formulas in this manual. 

 In actual practice only a few of the large number of known stains 

 are used; therefore, the type formulas and specific formulas of only the 

 most frequently used stains are given here. Detailed methods of using 

 these stains are described in the next section. 



THE HEMATOXYLIN STAINS 



1 he hematoxylin formulas rank among the most useful biological 

 stains. Hematoxylin is a natural dye, extracted from logwood, Hema- 

 toxylin campechianum L. The product is purchased in the form of 

 a j)ale yellow or brownish powder. The certified dye should be 

 specified. Hematoxylin is not a dye in itself, but in the presence of 

 certain alums, which serve as mordants, hematoxylin stains specific 

 cell structures. Numerous formulas and procedures appear in the 

 literature. There are two principal types of formula: (1) the self- 

 mordanting type, in which the hematoxylin dye, the alum mordant, 

 the oxidizing agent, and a preservative are in the same solution; 

 (2) the separate-mordant type, in which the mordant is first applied 

 to the tissues, followed by the application of the dye. 



Three of the most useful self-mordanting formulas are given 

 below: 



Mayer's Hemalum (Modified) 



Dissolve 20 g. potassium alum in 1 1. boiling water. 



Add 1 g. hematoxylin crystals to the above. Remove from the heater when 

 dissolved. 



Add 0.2 g. sodium iodate (NalOa) . 



The stain is ready to use at once. Filter whenever a metallic scum is visible 

 on the surface of the stain in the staining jar. The stain gradually disinte- 

 grates and should be made up fresh every 2 to 3 months. 



This stain can be made up more conveniently by using stock 

 solutions, thereby requiring only the relatively rough weighing of 

 the alum. Keep on hand a 5% solution of hematoxylin in 957c ethyl 

 alcohol. The dye dissolves slowly at 35°C. and requires about 2 

 weeks to attain a deep mahogany-red color. Store this solution in 

 a refrigerator, where it seems to keep its properties indefinitely. Make 

 up the stain as follows: 



Dissolve 20 g. potassium alum in 11. boiling water. 



Remove from the heater and add 20 cc. of the above alcoholic hema- 

 toxylin, drop by drop. 



Add 10 cc. of 2% NalOs 



