Gomori-Takamatsu procedure

a method for localizing the alkaline phosphatase enzyme: a tissue secretion is incubated in a buffered solution containing the substrate, glycerophosphate, and calcium ions; hydrolysis of the substrate releases phosphoric acid, and it combines with calcium and precipitates as calcium phosphate. This colorless precipitate is converted to brown cobalt sulfide, which is readily visualized with the microscope.