Which cell dissolves bone during remodeling?

• A. Osteoblasts
• B. Osteocytes
• C. Osteoclasts
• D. Fibroblasts

Answer: (C)

Bone remodeling hinges on a balance between breaking down old bone and building new bone. The dissolving part is carried out by osteoclasts, large multinucleated cells that attach to the bone surface and create a resorption pit. They acidify the local environment to dissolve mineral components like hydroxyapatite and release proteolytic enzymes to degrade the organic matrix. After this resorption, osteoblasts come in to lay down new osteoid that will mineralize. Osteocytes are former osteoblasts embedded in the bone matrix and help regulate remodeling, while fibroblasts form connective tissue elsewhere. So the cells that dissolve bone during remodeling are osteoclasts.