Building bone to reverse osteoporosis and repair fractures
J. Clin. Invest. Sundeep Khosla, et al. 118:421 doi:10.1172/JCI33612 [Go to this article.]

Figure 1
Histology (A–C; original magnification, ×40) and composite schematic (D) of the BRC, which comprises the cells constituting the BMU — specifically osteoclasts (OCs), osteoblasts (OBs), and osteocytes — as well as the canopy of bone-lining cells and the associated capillary. (A) BRC in cancellous bone, demonstrating the location of the OBs along the bone-forming surface. The osteocytes are shown embedded in the bone matrix and the canopy of cells consists of bone-lining cells. (B) BRC in cortical bone (outer demarcation indicated by the broken line) that is filled with erythrocyte ghosts (EG) and OBs; a few OCs are also seen. CV denotes the central vessel of the Haversian system, which forms the basic structural unit in cortical bone. (C) BRC stained with an antibody specific for CD34, which demonstrates staining of endothelial cells in the marrow capillary adjacent to the BRC. (D) Composite schematic of the BRC, showing connections between the osteocyte network, surface bone-lining cells, and the BRC. All cells in this network are connected with gap junctions, which might provide a pathway (arrows) by which signals generated by osteocytes deep within the bone reach the surface and elicit remodeling events by OCs and OBs. Note also the potential direct physical contact between OCs and OBs, which would allow for signaling between these cells. A and C are reproduced from Hauge et al. (7), and B and D from Eriksen et al. (10), with permission from the American Society for Bone and Mineral Research.