Endoconjonctive Ossification
The endoconjonctive ossification is the process of construction of the flat bones and the bone periostic.
The mésenchyme embryonic is transformed into a richly vascularized fabric (angiogénèse). The mésenchymateuses cells of fibroblastic type inclusent in the extracellular matrix rich in Collagène are aggrègent. These mésenchymateuses cells acquire a Phénotype osteoblastic and secrete proteins which constitute the osseous matrix. Many hearths of ossification develop, amalgamate and form by Anastomose a network of spans to the structure of a sponge, from where the name of spongy bone or primary education bone. This bone has a woven structure contrasting with the lamellate bone met later in the adult at the time of the replanning of the bone.
The Phosphate of calcium in the form of Hydroxyapatite (or ossopan) is the crucial factor of the mineralization of proteins secreted (collagenous of type I, Ostéocalcine, Ostéopontine, Ostéonectine and alkaline Phosphatase) by the osteoblasts. This mineralization leads to the imprisonment of the osteoblasts in ostéocytes and those of the vascularization which becomes a fabric hematopoietic. The ostéocytes remain connected between-them by canaliculi.
The final stages include the conversion of the spongy bone into lamellate bone; the lately synthesized collagen fibers are aligned in parallel beams. These plates are organized in a concentric way around a central vessel placed in the channel of Havers and form ostéones or system haversien. The bones membrane (or dermic) keep their spongy structure in the center, diploé ranging between the two blades of lamellate bone of the brain-pan. The périoste and the endoste result from the mineralization of the layers of conjunctive fabrics of the external and internal layers.
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