Medical Sciences 3999A/B/Y Lecture Notes - Lecture 15: Bone Resorption, Hyaline Cartilage, Vascular Endothelial Growth Factor
16 Feb 2020
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Document Summary
Flat bones of cranium e. g. parietal, frontal, part of occiput, temporal and maxillae, mandible and clavicle. Features primitive mesenchymal cells transform directly into osteoblasts (no intermediate cartilage model) Cells have elongated processes which make contact with adjacent cell processes --> forms network. Intercellular spaces are wide and filled with matrix - consists of collagen fibrils passing in various directions together with pgs. Development of matrix and differentiation of mesenchymal cells into osteoblasts. Processes of mesenchymal cells shorten and cells aggregate. Osteoid mineralized later; immature bone formed (initially irregularly shaped spicule and trabeculae) Long bones e. g. femur, humerus, radius, rib-cage, etc. Central chondrocytes mature to hypertrophy (synthesizes matrix type x collagen, alkaline phosphatase and vegf) Inner perichondrial cells in mid region of model start to form osteoblasts instead of chondroblasts. Covering is now periosteum (not perichondrium) --> osteoid. Bone collar or periosteal collar (formed by intramembranous ossification) Blood vessels and osteoprogenitors invade the space and start differentiating.
