Van Kossa staining shows which substance in tissue sections?

• A. Calcium
• B. Iron
• C. Sulfur
• D. Magnesium

Answer: (A)

Van Kossa staining is used to reveal mineralized deposits in tissue by staining calcium salts. The method uses silver nitrate to react with phosphate or carbonate in these salts, forming black silver deposits at sites of calcification. Because calcium in tissues is typically present as calcium phosphate or carbonate, this stain highlights calcium-containing calcifications. Thus, the substance demonstrated is calcium (calcium salts) in tissue sections. Iron, sulfur, and magnesium are detected with other stains, not van Kossa.