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The endosteum (pl.: endostea) is a thin vascular membrane of connective tissue that lines the inner surface of the bony tissue that forms the medullary cavity of long bones. [ 1 ] [ 2 ] This endosteal surface is usually resorbed during long periods of malnutrition , resulting in less cortical thickness.
These are the cells responsible for the resorption of bone. Osteoblasts are generally present on the outer layer of bone, just beneath the periosteum. Attachment of the osteoclast to the osteon begins the process. The osteoclast then induces an infolding of its cell membrane and secretes collagenase and other enzymes important in the resorption ...
Tartrate resistant acid phosphatase positive osteoclast in cell culture Illustrated cross-section of an activated osteoclast. An osteoclast is a large multinucleated cell and human osteoclasts on bone typically have four nuclei [5] and are 150–200 μm in diameter.
Components that are essential for osteoblast bone formation include mesenchymal stem cells (osteoblast precursor) and blood vessels that supply oxygen and nutrients for bone formation. Bone is a highly vascular tissue, and active formation of blood vessel cells, also from mesenchymal stem cells, is essential to support the metabolic activity of ...
Stromal cell-derived factor 1 (SDF-1) and CXCR4 mediate recruitment of mesenchymal stem cells. IL-1 and IL-6 are the most important cytokines for bone healing. IL-1 promotes formation of callus and of blood vessels. IL-6 promotes differentiation of osteoblasts and osteoclasts. [4] All cells within the blood clot degenerate and die.
The initiation of endochondral ossification starts by proliferation and condensation of mesenchymal cells in the area where the bone will eventually be formed. Subsequently, these mesenchymal progenitor cells differentiate into chondroblasts, which actively synthesize cartilage matrix components. Thus, the initial hyaline cartilage template is ...
Bone tissue is removed by osteoclasts, and then new bone tissue is formed by osteoblasts. Both processes utilize cytokine (TGF-β, IGF) signalling.In osteology, bone remodeling or bone metabolism is a lifelong process where mature bone tissue is removed from the skeleton (a process called bone resorption) and new bone tissue is formed (a process called ossification or new bone formation).
Volkmann's canals, also known as perforating holes or channels, are anatomic arrangements in cortical bones that allow blood vessels to enter the bones from periosteum.They interconnect the Haversian canals (running inside osteons) with each other and the periosteum.