Ossification

Ossification
The process of creating bone, that is of transforming cartilage (or fibrous tissue) into bone. The human skeleton initially consists largely of cartilage which is relatively soft and is gradually transformed into hard bone during infant and child development. The verb corresponding to "ossification" is "ossify." Cartilage becomes ossified as it is converted into bone. Bone is osseous tissue. "Os" is a synonym for "bone." The Latin word "os" means "bone" as does the related Greek word "osteon."
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1. The formation of bone. 2. A change into bone. [L. ossificatio, fr. os, bone, + facio, to make]
- endochondral o. formation of osseous tissue by the replacement of calcified cartilage; long bones grow in length by endochondral o. at the epiphysial cartilage plate where osteoblasts form bone trabeculae on a framework of calcified cartilage.
- membranous o. development of osseous tissue within mesenchymal tissue without prior cartilage formation, such as occurs in the frontal and parietal bones. SYN: intramembranous o..
- metaplastic o. the formation of irregular foci of bone (sometimes including bone marrow) in various soft structures, such as the muscles, lungs, brain, and other sites where osseous tissue is abnormal.

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os·si·fi·ca·tion .äs-ə-fə-'kā-shən n
1 a) the process of bone formation usu. beginning at particular centers in each prospective bone and involving the activities of special osteoblasts that segregate and deposit inorganic bone substance about themselves compare CALCIFICATION (a)
b) an instance of this process
2 a) the condition of being altered into a hard bony substance <\ossification of soft tissue>
b) a mass or particle of ossified tissue: a calcareous deposit in the tissues <\ossifications in the aortic wall>
os·si·fi·ca·to·ry 'äs-ə-fə-kə-.tōr-ē, -.tȯr-; esp Brit .äs-ə-fə-'kāt-(ə-)rē adj

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n.
the formation of bone, which takes place in three stages by the action of special cells (osteoblasts). A meshwork of collagen fibres is deposited in connective tissue, followed by the production of a cementing polysaccharide. Finally the cement is impregnated with minute crystals of calcium salts. The osteoblasts become enclosed within the matrix as osteocytes (bone cells). In intracartilaginous (or endochondral) ossification the bone replaces cartilage. This process starts to occur soon after the end of the second month of embryonic life. Intramembranous ossification is the formation of a membrane bone (e.g. a bone of the skull). This starts in the early embryo and is not complete at birth (see fontanelle).

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os·si·fi·ca·tion (os″ĭ-fĭ-kaґshən) [L. ossificatio] the formation of bone or of a bony substance; the conversion of fibrous tissue or of cartilage into bone or a bony substance.

Medical dictionary. 2011.

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Look at other dictionaries:

  • ossification — [ ɔsifikasjɔ̃ ] n. f. • 1697; de ossifier 1 ♦ Formation du tissu osseux par transformation d un tissu fibreux ou cartilagineux en substance osseuse. ⇒ ostéogenèse. Point, centre d ossification. Ossification des fontanelles. 2 ♦ Production… …   Encyclopédie Universelle

  • Ossification — Os si*fi*ca tion, n. [Cf. F. ossification. See {Ossify}.] 1. (Physiol.) The formation of bone; the process, in the growth of an animal, by which inorganic material (mainly lime salts) is deposited in cartilage or membrane, forming bony tissue;… …   The Collaborative International Dictionary of English

  • Ossification — (v. lat.), 1) Knochenbildung (s.d.); 2) Verknöcherung. Ossificationspunkte (Puncta ossificationis), die in einem nicht bleibenden Knorpel zuerst sich knöchern zeigenden Stellen, von denen die weitere Knochenbildung anhebt …   Pierer's Universal-Lexikon

  • Ossification — Ossification, lat. deutsch, Knochenbildung, Verknöcherung …   Herders Conversations-Lexikon

  • ossification — 1690s, from L. ossis (gen. of os) of bones (see OSSEOUS (Cf. osseous)) …   Etymology dictionary

  • Ossification — Bone is broken down by osteoclasts, and rebuilt by osteoblasts, both of which communicate through cytokine (TGF β, IGF) signalling. Ossification (or osteogenesis) is the process of laying down new bone material by cells called osteoblasts. It is… …   Wikipedia

  • Ossification — Ostéogenèse L ostéogenèse est le processus par lequel s élabore le tissu osseux. L os est formé à partir : d une matrice organique (35%) composée essentiellement de collagène de type I (90%), mais aussi d autres protéines comme l… …   Wikipédia en Français

  • ossification — (o ssi fi ka sion) s. f. 1°   Terme d anatomie. Génération des os, développement normal du système osseux. •   À deux mois, le foetus a plus de deux pouces de longueur ; l ossification est sensible au milieu du bras, de l avant bras, de la cuisse …   Dictionnaire de la Langue Française d'Émile Littré

  • OSSIFICATION — s. f. Formation des os, changement insensible des parties membraneuses et cartilagineuses en os. L ossification se fait peu à peu. L ossification du coeur, de l aorte. Le point d ossification …   Dictionnaire de l'Academie Francaise, 7eme edition (1835)

  • OSSIFICATION — n. f. Formation des os. Cet anatomiste a étudié l’ossification dans le foetus. Il se dit aussi du Changement insensible des parties membraneuses et cartilagineuses en tissu osseux. L’ossification du coeur, de l’aorte. Le point d’ossification …   Dictionnaire de l'Academie Francaise, 8eme edition (1935)

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