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→Development of Bone and Cartilage
Bone comprises the structure of the skeletal system and provide lever arms for locomotion. Bone also plays important roles in maintaining mineral homeostasis as well as providing the environment for hematopoesis in marrow.
Bone comprises the structure of the skeletal system and provide lever arms for locomotion. Bone also plays important roles in maintaining mineral homeostasis as well as providing the environment for hematopoesis in marrow.
==Development of Bone and Cartilage==
==Development of Bone and Cartilage==
*Osteogenesis
**'''Intramembranous Ossification'''
***Forms the '''flat''' bones of skull and mandible
***No cartilaginous precursor: mesenchyme forms bone directly
****Mesenchyme condenses, differentiates to pre-osteoblasts, then osteoblasts
****Osteoblasts synthesize osteoid (collagen and proteoglycans)
****Mineralization and Bone Spicule formation (spicules produce spongy bone)
****Appositional Growth: laid down on the exterior (vs interior) surface of developing bone
***Increasing association with blood vessels
***Bone Marrow formed by mesenchyme between bone and blood vessels
**'''Endochondral Ossification'''
***Responsible for embryonic bone formation as well as growth in length
***Via cartilaginous precursor:
****Mesenchyme condenses to form bone outline
****Core cells differentiate to chondroycytes and begin secreting cartilage matrix
****Peripheral condensation forms perichondrium
****Interstitial (length) and Appositional (width) growth
****Central cells in developing diaphysis mature and hypertrophy
****Matrix surrounding most mature chondrocytes calcifies
****Perichondrium differentiates to osteoblasts
***Capillary invasion to central core, forming trabecular bone
==Types of Bone==
==Types of Bone==