Mallory's Phosphotungstic Acid-Hematoxylin is used to demonstrate cross-striations in which tissue feature?

• A. Muscle cross-striations
• B. Nuclei
• C. Nerve fibers
• D. Epithelial cells

Answer: (A)

Cross-striations are the repeating sarcomere units seen in striated muscle. Mallory's Phosphotungstic Acid-Hematoxylin stains the muscle’s myofibrillar proteins in a way that highlights this banded pattern, making the alternating dark and light bands along muscle fibers easily visible under light microscopy. This staining is specific to the organized contractile apparatus of striated muscle, so you can clearly see cross-striations. Nuclei, nerve fibers, and epithelial cells do not display this striated pattern, and their structures are highlighted differently by other stains. Thus, the stain best demonstrates cross-striations in skeletal (striated) muscle fibers.