Figure 2-3. Bone Remodeling.

Figure 2-3Bone Remodeling

Note: The sequence of activation, resorption, reversal, and formation is illustrated here. The activation step depends on cells of the osteoblast lineage, either on the surface of the bone or in the marrow, acting on blood cell precursors (hematopoietic cells) to form bone-resorbing osteoclasts. The resorption process may take place under a layer of lining cells as shown here. After a brief reversal phase, the osteoblasts begin to lay down new bone. Some of the osteoblasts remain inside the bone and are converted to osteocytes, which are connected to each other and to the surface osteoblasts. The resorption phases last only a few weeks but the formation phase is much slower, taking several months to complete, as multiple layers of new bone are formed by successive waves of osteoblasts.

From: 2, The Basics of Bone in Health and Disease

Cover of Bone Health and Osteoporosis
Bone Health and Osteoporosis: A Report of the Surgeon General.
Office of the Surgeon General (US).
Rockville (MD): Office of the Surgeon General (US); 2004.

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