osin is the name of several fluorescent acidic compounds which bind to and form salts with basic, or eosinophilic, compounds like proteins containing amino acid residues such as arginine and lysine, and stains them dark red or pink as a result of the actions of bromine on eosin.
The Giemsa′s azur-eosin-methylene blue dye is a dry dye that is used for the preparation of a staining solution. This solution can be used for the staining of blood and bone marrow smears, paraffin sections, spirochaets and clinical-cytological specimens of human origin.
Eosin is anionic and acts as an acidic dye. It is negatively charged and can react with positively charged, acidophilic components in the tissue, such as amino groups in proteins in the cytoplasm. These stain pink as a result
