Eosin Y solutions are regularly used as counterstains to hematoxylin in histology staining method, the HE (hematoxylin-eosin) staining. This method achieves better cellular structure visualization and differentiation. The microscopic samples’ nuclei are stained blue using hematoxylin, then they are stained various shades of pink using cytoplasm eosin. Eosin Y is a fluorescein derivative. As color powder it can be used as a reagent mixture often used in histological, but also in cytological methods of staining, such as the Papanicolaou method in exfoliative cytology or for creating Romanowsky dyes. Eosin Y is anion dye which stains erythrocytes bright red, and it also stains basic cellular components, such as cytoplasm, collagen, and muscle fibers. BioGnost’s Eosin Y Instant, aqueous and alcoholic preparations are very easily dissolved in water or in 70% alcohol. They are ready for instant use.