Bone Remodeling

This slide shows the activation-resorption-formation sequence of bone remodeling. Begin on the left by identifying a multinucleate osteoclast as it breaks down the adjacent bone matrix. This osteoclast became active through the RANK/RANK-L signaling system. The ruffled border lies between the osteoclast and the matrix and is where enzymes are secreted to degrade the mineral deposits and osteoid tissue. In the center of the image is the site of reversal, where the population shifts from osteoclasts to osteoblast precursors. On the right side of the image are differentiated osteoblasts that are forming osteoid. The border between the old and new bone tissue is the cement line.