الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Bone is a mineral connective tissue with four cell types : osteoblasts, osteoclasts , bone lining cells and osteocytes and (Buckwalter et al., 1996) ,(Downey and Siegel, 2006). Bone serves key tasks in the body, including mobility, support and protection, calcium and phosphate and bone marrow storage (Datta et al., 2008), (Robling et al., 2006). Despite its apparent inertness, bone is a rapidly changing organ that is constantly resorbed by osteoclasts and formed by osteoblasts. There is indication that osteocytes have a role as mechanosensors and orchestrators in the bone remodelling process. (Clarke, 2008), (Bonewald, 2011). The role of bone lining cells is unknown, however they appear to play a crucial role in linking bone resorption and bone creation. (Everts et al., 2002). Bone remodelling is a very complicated process in which old bone is replaced with new bone in a three-phase cycle: (1) Osteoclasts initiate bone resorption, (2) the transition from resorption to new bone creation, and (3) osteoblasts initiate bone synthesis. (Sims and Gooi, 2008) (Matsuo and Irie, 2008). This happens as a result of the coordinated efforts of osteoclasts, osteocytes, osteoblasts and bone lining cells, which create the transient anatomical structure defined as basic multicellular unit (BMU) (Andersen et al., 2009) (Hauge et al., 2001). Normal bone remodelling is required for fracture healing, mechanical adaptability of the skeleton, and calcium homeostasis. (Dallas et al., 2013).