Biomineralization课件.ppt

Biomineralization;Lecture Outline;What is Biomineralization?;Definition;Examples;Examples;Many Functions;General Biomineralization Mechanism;Why do we care about calcification?;Why do we care about calcification?;Bone;Endochondral Ossification;Formation of long bones examples: humerus, radius, ulna, femur, tibia, fibula Mesenchymal cells migrate to site of bone formation Mesenchymal cells give rise to chondrocytes and form the shape of bone Chondrocytes secrete ECM Chondrocytes continue to grow until they become encapsulated in the ECM Primary ossification Mature chondrocytes hypertrophy Cartilage matrix becomes calcified, which may be mediated by matrix vesicles Calcified matrix is partly degraded by osteoclasts, allowing blood vessels and osteoprogenitor cells to invade Osteoprogenitor cells become osteoblasts, which lay down new bone after using the calcified matrix as a template Osteoblasts secrete osteoid Osteoid is the organic part of bone without the inorganic constituent Osteoid becomes calcified and osteoblasts that remain become encapsulated into the calcified matrix and are now called osteocytes Process of bone formation continues toward both epiphyses Cartilage outside the primary ossification center increases in size by interstitial and appositional growth Secondary ossification occurs at the ends of each epiphysis similar process as primary ossification growth continues until cartilage between the ossification centers is replaced completely by bone (growth plate) Bone remodeling occurs osteoclasts resorb bone areas of bone not completely filled in are called cancellous bone areas filled in are called compact bone Medullary cavity for bone marrow formed ;Intramembranous Ossification;Intramembranous Ossification;Bone Calcification;What Initializes Bone Calcification?;What are Matrix Vesicles?;Where are Matrix Vesicles Made?;Composition of Matrix Vesicles;Composition of Matrix Vesicles;Matrix Vesicle Functions;Matrix Vesicle Functions;Proposed Mech