Romanowsky type stains are combinations of which dyes?

• A. Acid and basic dyes
• B. Only basic dyes
• C. Only acidic dyes
• D. Metallic dyes

Answer: (A)

Romanowsky-type stains rely on a mixture of dyes with opposite charges to create differential coloration of cellular components. A basic dye (like methylene blue or azure stains) binds to negatively charged structures such as nucleic acids and rough endoplasmic reticulum, coloring them blue to purple. An acidic dye (like eosin) binds to positively charged components, staining cytoplasmic elements and many extracellular matrix proteins pink or red. The combination yields a multicolored preparation that clearly distinguishes nuclei, cytoplasm, and granules, which is why these stains are described as using both acidic and basic dyes. Metallic dyes aren’t part of this approach.