Presentation on theme: "Bone Development (during fetal development)"— Presentation transcript:
1 Bone Development (during fetal development) Intramembranous ossificationTakes place in connective tissue membraneEndochondral ossificationTakes place in cartilageBoth methods of ossificationProduce woven bone that is then remodeledAfter remodeling, formation cannot be distinguished as one or other
2 Intramembranous Ossification (8th week – 2 years of development) Takes place in connective tissue membrane formed from embryonic mesenchymeForms many skull bones, part of mandible, diaphyses of claviclesWhen remodeled, indistinguishable from endochondral bone.Centers of ossification: locations in membrane where ossification begins (centers of ossification expand outwards to form a bone by gradually ossifying the membrane)Fontanels: large membrane-covered spaces between developing skull bones; unossified (bones eventually grow together & all fontanels have closed by 2 years of age)
4 Endochondral Ossification Bones of the base of the skull, part of the mandible, epiphyses of the clavicles, and most of remaining bones of skeletal systemCartilage formation begins at end of fourth week of developmentSome ossification beginning at about week eight; some does not begin until years of age
9 Growth in Bone Length Growth in length occurs at the epiphyseal plate Involves the formation of new cartilage byInterstitial cartilage growthAppositional growth on the surface of the cartilageClosure of epiphyseal plate: epiphyseal plate is ossified becoming the epiphyseal line. Between 12 and 25 years of ageArticular cartilage: does not ossify, and persists through lifeAppositional growth onlyInterstitial growth cannot occur because matrix is solidOccurs on old bone and/or on cartilage surface
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