12 Biological Stains 



Ehrlich (1910), Krause (1926-7), Lee (1950, and earlier editions), 

 McClung (1951, and earlier editions). 



Animal microtechnic. Although the earliest uses of stains were 

 botanical, modern histological technic was first developed on 

 zoological material. As a result the first extensive use of stains 

 was in animal histology. It is still true that there are many more 

 staining procedures developed in animal histology than in plant 

 histology, and that many more dyes are thus employed in the 

 former field than in the latter. (This is not true, as will be ex- 

 plained below, in regard to cytological methods.) 



In animal histology one thinks first of the general tissue stains. 

 These involve the use of one, two, and occasionally three dyes in 

 staining sections of general animal tissue designed primarily to 

 differentiate nuclei from cytoplasm of cells and to permit dis- 

 tinctions between the various types of tissue. Best known of 

 these are the various procedures calling for hematoxylin, some- 

 times alone and sometimes with a counterstain, such as eosin Y, 

 Congo red, or safranin; the hematoxylin-eosin combination is in 

 such general use that it is commonly referred to as the "H-E 

 stain". Although these hematoxylin procedures have received 

 many modern refinements, they date back to the 19th century and 

 still bear the names of Heidenhain, Delafield, and Mayer, men 

 who did their chief work in the eighties and nineties. Also in- 

 cluded among the general tissue stains are various combinations 

 of basic dyes such as crystal violet, methylene blue or one of the 

 azures, with some contrasting acid dye such as eosin Y; the former 

 to stain the nuclei, the latter, the cytoplasm of the cells. 



Somewhat more specialized in their application are the con- 

 nective tissue stains. The distinction between them and the general 

 tissue stains is more or less arbitrary, particularly because some 

 procedures that bring out connective tissue and elastin to good ad- 

 vantage are also fine general tissue stains. The grouping can, 

 however, be made in a rough way and for practical purposes is 

 rather convenient. Of special note among the connective tissue 

 stains is a triple-staining procedure proposed by Mallory, which in 

 its original form called for the dyes, anilin blue, orange G, and 

 acid fuchsin; its important feature is mordanting in phosphotungs- 

 tic acid before applying the final staining fluid. It has been 

 variously modified in recent years and the variants are usually 

 called modifications of the "Mallory anilin blue connective tissue 

 stain", although some of them omit the anilin blue entirely. 

 Among connective tissue stains are also included a variety of 

 double, triple, and even quadruple stains of a miscellaneous nature, 

 and the well-known Mallory phosphotungstic acid hematoxylin 

 method, in wdiich such strong polychrome properties of the dye 

 are developed that no counterstain is necessary to secure proper 

 differentiation of tissue. 



