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

• A. True
• B. False
• C. Only blue staining
• D. It has no effect

Answer: (B)

In PTAH staining, the red color marks muscle fibers and related cytoplasmic elements, while blue marks neurofibrils and other structures stained by the hematoxylin component. The red reaction product is sensitive to prolonged aqueous washing and can fade with extended rinsing. Washing helps remove excess stain, but if the rinse time is too long, the red staining diminishes, and the blue staining becomes more prominent by comparison. So, prolonged washing will not enhance the red staining; it actually decreases it.