ANAT 416 Lecture Notes - Lecture 21: Intramembranous Ossification, Endochondral Ossification, Haversian Canal
3 Jun 2020
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Apr 4 // lec 21 // bone dev // p siegel. Connective tissue, lines inner bone surfaces adjacent to marrow space. Haversian canals for blood vessels, with surrounding layers/lamella that form osteons (repeating units) and the lamella between them. This lamellar network of bone traps osteocytes, which are alive bone cells. Porous, in epiphysis + vertebrae, low density, lattice of trabeculae. Bone tissue is composed of mineral + protein matrix deposited by cells. 90% type 1 collagen, some collagen ii, v, x. Non-collagenous proteins (ncp) exist too, regulate mineralization (+/-) Secrete col1a1 and ncps to make osteoid (col1a1 and ncp are markers of blasts) Extensive syncytium network for nutrient/waste movement within compact bone, maintain bone quality by surveillance (if network breaks, they respond) Monocyte/hsc origin --> become polynucleated to polykaryon --> terminally diff"d as activated osteoclast. Form ruffled border to incr sa of bone. Protons (demineralize) and proteases (cut collagen) secreted into ecm space to dissolve it.
