Ossification is the process of bone formation, in which connective tissues, such as cartilage are turned to bone or bone-like tissue. The ossified tissue is invaginated with blood vessels. These blood vessels bring minerals like calcium and deposit it in the ossifying tissue. Bone formation is a dynamic process, with cells called osteoblasts depositing minerals, and osteoclasts removing bone.[1] This process, termed bone remodeling continues throughout life.[2]
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Types of ossification
- Endochondral ossification: formation of bone by replacement of hyaline cartilage.
- Intramembranous ossification: formation of bone from mesenchyme, esp. flat bones found in the skull
- Heterotopic ossification: formation of bone in extraskeletal soft tissue, esp. in connective tissue or muscle tissue
Evolution
Several hypotheses have been proposed for how bone evolved as a structural element in vertebrates. One popular idea is that bone developed from tissues that evolved to store minerals. In this model, minerals such as calcium were stored in cartilage, and that bone was an exaptation from this ossified cartilage.[3] However, other possibilities include bony tissue evolving as an osmotic barrier, or as a protective structure.
References
- ^ Caetano-Lopes J, Canhão H, Fonseca JE (2007). "Osteoblasts and bone formation". Acta reumatológica portuguesa 32 (2): 103–10. PMID 17572649.
- ^ Hadjidakis DJ, Androulakis II (2006). "Bone remodeling". Ann. N. Y. Acad. Sci. 1092: 385–96. PMID 17308163.
- ^ Donoghue PC, Sansom IJ (2002). "Origin and early evolution of vertebrate skeletonization". Microsc. Res. Tech. 59 (5): 352–72. PMID 12430166.
External links
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| Cartilage | perichondrium, fibrocartilage callus, metaphysis
cells (chondroblast, chondrocyte) types (hyaline, elastic, fibrous) |
| Bone | ossification (intramembranous, endochondral, epiphyseal plate)
cycle (osteoblast, osteoid, osteocyte, osteoclast) types (cancellous, cortical) regions (epiphysis, metaphysis, diaphysis) structure (osteon/Haversian system, Haversian canals, endosteum, periosteum, Sharpey's fibres, enthesis, lacunae, canaliculi, trabeculae, medullary cavity, bone marrow) shapes (long, short, flat, irregular, sesamoid) |
