الفهرس 
CHAPTER 1: LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Long bone development and growth occur through endochondral ossification, which occurs during embryonic development. During embryonic development, the mesenchymal tissue transformed into a cartilage template and the bone tissue is formed on remnants of this cartilage tissue. The growth cartilage of the long bone is formed of chondrocytes which secrete and maintain the surrounding cartilage extracellular matrix. The chondrocytes of the growth cartilage are organized into three dynamic zones; resting, proliferative and hypertrophic zones. Resting cells act as stem cells for the proliferative chondrocytes. The proliferative chondrocytes undergo a continuous division and differentiation into hypertrophic chondrocytes. Hypertrophic chondrocytes die by a mechanism described by many authors as apoptosis; however some recent studies confirmed the hypertrophic chondrocytes die by non-apoptotic modes of physiological