Information: Eosin Y Solution (Aqueous) is intended for use in the histological demonstration of cytoplasm and is commonly used as a counterstain for Hematoxylin. When used correctly, various shades of pink can be obtained to aid in visualization of tissue components. Erythrocytes, collagen, and the cytoplasm of muscle or epithelial cells will stain with different shades of pink. Cytoplasm: Pink to Red Erythrocytes Pink to Red Nuclei: Black/Blue (Hematoxylin)