A small osteoclast with two nuclei can be seen in the endosteum (HA4, arrow). Osteoclasts are monocyte-derived, multinucleated cells that demineralize and destroy bone. Other cells in the endosteum include osteoprogenitor cells and fibroblasts. Osteoblasts touch the surface of the bone. At this magnification, you can see the nuclei and cytoplasms of several osteocytes that are living in lacunae.