VonKossaFärbung

The Von Kossa stain is a histochemical technique used to detect calcium deposits within biological tissues. Developed by German physician and pathologist Gustav Von Kossa, it is primarily employed in microscopic examination to identify areas of calcification, particularly in bone, cartilage, and pathological conditions like atherosclerosis or kidney stones. The stain relies on the principle that calcium ions react with silver nitrate in the presence of light to form a black precipitate of silver phosphate.

To perform the Von Kossa stain, tissue sections are typically demineralized or fixed, then immersed in a solution of silver nitrate. Exposure to a light source, often UV light or direct sunlight, initiates the reaction, causing the silver ions to precipitate in the presence of phosphate ions liberated from the calcium salts. Subsequent washing removes unreacted silver nitrate, and the stained sections are then counterstained with a contrasting color, such as nuclear fast red or hematoxylin, to visualize cellular structures. Calcified areas will appear distinctly black or dark brown against the lighter background of the counterstain, making them readily identifiable. The Von Kossa stain is a valuable tool for pathologists and researchers investigating conditions involving abnormal calcium deposition and bone mineralization.