Which statement about Phosphotungstic acid-hematoxylin (PTAH) is supported by the material?

• A. It stains muscle blue, demonstrates cross striations, and stains collagen reddish orange
• B. It stains nuclei green
• C. It stains fat yellow
• D. It stains bacteria purple

Answer: (A)

Phosphotungstic acid-hematoxylin is a differential stain used to visualize muscle fibers and connective tissue. It colors muscle blue and makes the cross-striations within the muscle fibers clearly visible, while collagen in the surrounding connective tissue takes on a reddish-orange hue. This contrast—blue muscle fibers with blue cross-striations against reddish-orange collagen—is a hallmark of PTAH staining and is what makes the statement correct. It’s not a stain that colors nuclei green, fats yellow, or bacteria purple, which are seen with other staining methods.