Ultrastructure, tartrate-resistant acid phosphatase activity and calcitonin responsiveness of osteoclasts at sites of demineralized bone matrix implant-induced osteogenesis.

The morphology, ultrastructure, tartrate-resistance acid phosphatase reactivity, and calcitonin responsiveness of osteoclasts induced at sites of demineralized bone matrix (DBM) implant-induced osteogenesis in rats were determined. Osteoclasts at these ectopic sites had a morphologic and ultrastructural appearance similar to osteoclasts normally found in skeletal tissues. When observed by scanning electron microscopy, resorption surfaces on the implants had well-defined resorption pits (Howship's lacunae), indicative of active bone resorption. The osteoclasts stained intensely for tartrate-resistance acid phosphatase, an enzyme that is specific for osteoclasts. In response to human calcitonin, hypocalcemia occurred and osteoclasts lost their ruffled borders, indicating that these cells are responsive to exogenous hormonal stimulation. The osteoclasts induced by subcutaneous implantation of DBM had morphologic and functional characteristics similar to osteoclasts normally found in skeletal tissues.