Used in histology and pathology to detect alkaline phosphatase enzyme activity in tissue sections. The stain helps visualize sites of enzymatic activity by forming a visible precipitate at the location of the enzyme. Commonly applied in bone and liver tissue studies, where alkaline phosphatase is highly active. It aids in diagnosing bone disorders such as rickets or osteomalacia and can identify cholestasis or other liver diseases. The method uses calcium and cobalt salts to capture the phosphate released by the enzyme, resulting in a brown or black deposit that marks positive areas under the microscope. Widely used in research and clinical labs for cellular localization of enzyme expression in frozen or fixed tissue samples.