Immunocytochemical localization of cathepsins B and G in odontoclasts of human deciduous teeth.

For clarification of the mechanisms by which odontoclasts resorb deciduous teeth during physiological root resorption, cysteine-proteinases such as cathepsins B and G were immunocytochemically localized in odontoclasts at the ultrastructural level. Extracted human deciduous teeth undergoing root resorption were fixed with a mixture of formaldehyde and glutaraldehyde and processed for immunocytochemical detection of these enzymes. Sheep antisera, raised against either human cathepsin B or G, were used as primary antibodies. In odontoclasts, specific immunogold labeling of both anti-cathepsin B and G was clearly localized in lysosomes and pale vacuoles of various sizes, and in a portion of the extracellular canals of odontoclastic ruffled borders. In the presence of either antibody, the cytoplasmic matrix, mitochondria, and nuclei were minimally labeled by immunogold particles. The presence of these proteolytic enzymes in odontoclasts suggests that, during odontoclastic root resorption, these enzymes are involved in the formation of resorption lacunae by means of intra/extracellular degradation of collagen and other non-collagenous matrix proteins of deciduous teeth.