【摘 要】
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INTRODUCTIONrnVertebrate skeletal development occurs through intramembra?nous and endochondral ossification. Intramembranous ossification involves the direct di
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Department of Orthopaedics, Brown University Alpert Medical School and Rhode Island Hospital, Provid
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INTRODUCTIONrnVertebrate skeletal development occurs through intramembra?nous and endochondral ossification. Intramembranous ossification involves the direct differentiation of mesenchymal stem cells into osteoblasts and is responsible for the ossification of cranial bones and for appositional bone growth.1–2 Endochondral ossification requires the formation of cartilaginous anlagen and their subsequent replacement by osteoblasts, and contributes to longitudinal bone growth.3–4 During endochondral ossification, mesenchymal cells condense and then differentiate into early proliferating chondrocytes, which undergo further differentiation to establish a cartilage growth plate. Cells within growth plates are organized into distinct zones containing resting, proliferating, pre?hypertrophic, and hypertrophic chondrocytes. Hypertrophic chon?drocytes undergo apoptosis and are replaced by osteoblasts or transdifferentiate into osteoblasts, which produce bone.
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