BISC 104Lxg Lecture Notes - Lecture 6: Bone Remodeling, Thyroid, Epiphyseal Plate
1 Feb 2017
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Document Summary
During embryonic development, most of the skeleton is first formed of cartilage. Unlike mature bone cells, which are enclosed in a solid matrix, cartilage cells are capable of dividing. The cartilage model can grow as rapidly as the fetus does. Beginning at the third month and through prenatal development, the cartilage is gradually replaced by bone. Begins when osteoblasts form a collar of bone around the shaft of the cartilage model. Osteoblasts then migrate to the bone cavity to form spongy bone. Cartilage cells within the growth plate divide, forcing the end of the bone farther away from the shaft. As bone replaces the newly formed cartilage in the region closer to the shaft, the bone lengthens. The bone diameter also enlarges as the bone lengthens. Two regions of cartilage remain at each end of the long bone - the cap that covers the surfaces that rub against other bones and the growth plate, or epiphyseal plate.
