INTEGBI 131 Lecture Notes - Lecture 3: Intramembranous Ossification, Endochondral Ossification, Hyaline Cartilage
24 Sep 2018
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Document Summary
Endochondrial ossification: all bones except some bones e. g. , some skull bones and clavicles, bones are modeled in hyaline cartilage, begins forming late in the 2nd month of embryonic development, continues forming until early adulthood. Primary ossification centers in skeleton of 12 week old fetus: parietal bone, occipital bone, frontal bone of skull, mandible, clavicle, scapula, radius, ulna, Bone deposition and resorption: occurs at periosteal (periosteum) and endosteal (endosteum) surfaces. In adults, this occurs primarily at the endosteal surface. Bone remodeling: bone deposition/formation- accomplished by osteoblasts, bone resorption- accomplished by osteoclasts, maintains normal levels of ca+ and po4, bone is remodeled in response to mechanical stress it experiences. Osteoclast: a bone-degrading cell: a giant cell with many nuclei, derived from hematopoietic stem cells, crawls along bone surfaces, breaks down bone tissue, secretes concentrated hcl, released lysosomal enzymes, may also phagocytize collagen and dead osteocytes.
