The use of the potassium pyroantimonate-osmium method as a means of identifying and localizing calcium at the ultrastructural level in the cells of calcifying systems.

Potassium pyroantimonate-osmium has been used to localize calcium as an electron dense precipitate in the odontoblast, ameloblast and early hypertrophic chondrocytes of the mandibular condylar growth cartilage. The precipitate exhibited a specific association with various cell organelles. The presence of calcium in the precipitates was confirmed using energy dispersive analysis by x-rays. It is suggested that this K-pyroantimonate method provides an accurate technique for the investigation of the subcellular localization of calcium in calcifying systems.