Osteoclast

These multinucleated osteoclasts are much larger cells when compared with all other bone cells and their precursors. Because of their size, they can be identified very easily under light microscope. These are often seen in clusters. Under electron microscope, the cell membrane (adjacent to the tissue surface) is thrown into a myriad of deep folds that form a ruffled border. At the periphery of this border, the plasma membrane is apposed closely to the bone surface; the adjacent cytoplasm is devoid of cell organelles and is enriched in actin, vincoline, and taline proteins (provides integrin-mediated cell adhesion). This clear or ceiling zone not only attaches the cell to the mineralized surface but also isolates a microenvironment between them and the bone surface. Osteoclasts are large multinucleated cells appearing at or near the surface of bone undergoing resorption. They are typically located in cavities or pits (Howship’s lacunae) on the bone surface, where it participates in the constant process of bone remodeling.