Prolonged washing of sections stained with PTAH will enhance the red staining of certain tissue components.

• A. True
• B. False
• C. It enhances blue staining
• D. Has no effect

Answer: (B)

Understanding PTAH staining helps explain why this statement isn’t true. In PTAH, the red color marks contractile elements in muscle fibers and certain cytoplasmic components, while blue-black marks connective tissue and fibrin. The red pigment formed during PTAH is not particularly stable to prolonged washing; extended washing tends to wash out or diffuse the red precipitate, leaving the blue staining relatively more prominent. Because of this, prolonged washing does not enhance the red staining—in fact, it often reduces it.