Neutral Stains: the Romanowsky — Giemsa Methods

Abstract

In previous chapters we have dealt with ‘acid’ and `basic’ dyes (see chapters 5 and 6). When these acid dyes are combined with other acid dyes, there is no chemical interaction. The same is true for a combin-ation of basic dyes. However, a different situation arises when an acid dye and a basic dye are put in the same solution. In that case the coloured anion and the coloured cation may combine, forming a coloured salt. Such a solution is described as neutral. The salt as such can react with certain cell components. In addition, the acid component and the basic component of the neutral stain can react with other cell elements. Thus all three, the salt, the cation and the anion, can colour different cell components. Because of this threefold action, a neutral stain can produce a very useful differentia-tion of cell components in one staining bath.