Osteoclast cells on bone, illustration - Bildbanksillustration

Illustration of osteoclast cells (red) on the surface of bone tissue. Osteoclasts are large, multi- nucleated cells that form from the fusion of several macrophage cells in bone. They are normally present in bones to absorb and remove unwanted bone tissue during normal bone regeneration. In osteoporosis increased activity of the cells contributes to the weakening of the bone and increased risk of fractures