[Detection of calcium in tissues using alizarin red S and optical properties of the reaction product]

A histological method of staining calcium deposits in organs and tissues is presented. Staining at different pH provides a certain differentiation of the characteristics of calcium deposits. Further findings concern optical properties of the reaction product of staining observed at examination in polarized light, differential interference contrast (OPTON), and by fluorescence microscopy. The chemical nature of the Alizarin red S reaction product in sites of calcium deposits is discussed.