ABSTRACT
This chapter is devotesd to the thiazine eosinates, which are used principally for identifying cells in blood and hemopoietic tissues. Earlier work with neutral stains was based on the assumption that a mixture of thiazine dyes, combined with an eosin, was necessary in order to obtain the expected combination of colors in a stained blood film. The purple product of Romanowsky-Giemsa staining does not form instantaneously. Ehrlich believed that the granules of polymorphonuclear leukocytes were colored by both anionic and cationic components of his ‘triacid’ stain, and that is why he called them neutrophils. He regarded the specific dyeing of these granules as an important property of neutral stains, not to be obtained without their use. The heparin-containing granules are stained blue–violet by azure B alone, and purple by azure B–eosin Y. This appears to be a true Romanowsky-Giemsa effect, and it cannot be copied by eosin Y combined with other cationic dyes.
