Osteclaster

Osteclaster is a term that may appear in older or nonstandard writings as an alternative spelling for osteoclast, the bone-resorbing cell. In modern anatomy and physiology, osteoclast is the accepted term. The possible usage of osteclaster derives from Greek roots for bone (osteon) and breaking or crushing (clastos), but it is not widely used in current literature.

Osteoclasts are large, multinucleated cells formed from hematopoietic precursors. They attach to the bone surface at a specialized sealing zone and create a resorption lacuna where bone is dissolved. They acidify the local environment with proton pumps and secrete proteolytic enzymes such as cathepsin K, enabling removal of mineral and organic matrix. Their formation and activity are regulated by RANKL and M-CSF, with osteoprotegerin acting as a decoy receptor to inhibit signaling. They work in concert with osteoblasts during bone remodeling.

Disordered osteoclast activity underlies several disorders. Excessive resorption is characteristic of osteoporosis and osteolytic lesions in cancer, while insufficient activity can lead to overly dense bones seen in osteopetrosis. Therapeutic approaches often target osteoclasts, including bisphosphonates that impair resorption and denosumab, a monoclonal antibody against RANKL. Because osteclaster is not a standard term, readers are advised to favor osteoclast in formal contexts.