WordNet

the calcification of soft tissue into a bonelike material
the developmental process of bone formation
the process of becoming rigidly fixed in a conventional pattern of thought or behavior
hardened conventionality (同)conformity
natural process that causes something to form; "the formation of gas in the intestine"; "the formation of crystals"; "the formation of pseudopods"
the act of fabricating something in a particular shape (同)shaping
a particular spatial arrangement
creation by mental activity; "the formation of sentences"; "the formation of memories"
an arrangement of people or things acting as a unit; "a defensive formation"; "a formation of planes"
remove the bones from; "bone the turkey before roasting it" (同)debone
the porous calcified substance from which bones are made (同)osseous_tissue
consisting of or made up of bone; "a bony substance"; "the bony framework of the body"
a shade of white the color of bleached bones (同)ivory, pearl, off-white
rigid connective tissue that makes up the skeleton of vertebrates (同)os
having bones as specified; "his lanky long-boned body"
having had the bones removed; "a boneless rib roast"; "a boned (or deboned) fish" (同)deboned
a percussion instrument consisting of a pair of hollow pieces of wood or bone (usually held between the thumb and fingers) that are made to click together (as by Spanish dancers) in rhythm with the dance (同)castanets, clappers, finger cymbals

PrepTutorEJDIC

〈U〉骨化 / 〈C〉骨化して部分
〈U〉(…の)『形成』,構成,育成《+『of』+『名』》 / 〈C〉形成されたもの,構成物;(その)構造,組織 / 〈U〉〈C〉隊形,陣形
〈C〉骨 / 〈U〉骨を作っている物質,骨質 / 《複数形で》骨格;死骸(がい) / 〈魚など〉‘の'骨を取る
(魚など)骨を取り除いた / (衣服が)(コルセットなどで)骨で張りをつけた[ような]

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/12/08 17:23:18」(JST)

wiki en

[Wiki en表示]

Look up ossification in Wiktionary, the free dictionary.

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 synonymous with bone tissue formation. There are two processes resulting in the formation of normal, healthy bone tissue:^[1] Intramembranous ossification is the direct laying down of bone into the primitive connective tissue (mesenchyme), while endochondral ossification involves cartilage as a precursor. In fracture healing, endochondral osteogenesis is the most commonly occurring process, for example in fractures of long bones treated by plaster of Paris, whereas fractures treated by open reduction and stabilization by metal plate and screws may heal by intramembranous osteogenesis.

Heterotopic ossification is a process resulting in the formation of bone tissue that is often atypical, at an extraskeletal location. Calcification is often confused with ossification. Calcification is synonymous with the formation of calcium-based salts and crystals within cells and tissue. It is a process that occurs during ossification, but not vice versa.

The exact mechanisms by which bone development is triggered remains unclear, but it involves growth factors and cytokines in some way.

Timetable for human ossification[edit]

Time period^[2]	Bones affected^[2]
Third month of embryonic development	Ossification in long bones beginning
Fourth month	Most primary ossification centers have appeared in the diaphyses of bone.
Birth to 5 years	Secondary ossification centers appear in the epiphyses
5 years to 12 years in females, 5 to 14 years in males	Ossification is spreading rapidly from the ossification centers and various bones are becoming ossified
17 to 20 years	Bone of upper limbs and scapulae becoming completely ossified
18 to 23 years	Bone of the lower limbs and os coxae become completely ossified
23 to 25 years	Bone of the sternum, clavicles, and vertebrae become completely ossified
By 25 years	Nearly all bones are completely ossified

Intramembranous ossification

Intramembranous ossification forms the flat bones of the skull, clavicle and mandible. A detailed description of the process can be found at the page for Intramembranous Ossification.

Endochondral ossification is the formation of long bones and other bones. This requires a hyaline cartilage precursor. There are two centres of ossification for endochondral ossification.

The primary centre

Bones first appear in the diaphysis (middle of shaft), Chondrocytes multiply and form trebeculae. (spongy bone). Cartilage is progressively eroded and replaced by hardened bone, extending towards the epiphysis. Perichondrium layer surrounding the cartilage forms the periosteum, which generates osteogenic cells that then goes on to make a collar that encirclces the outside of the bone and remodels the medullary cavity on the inside. NOTE: most other bones (e.g. vertebrae) also have primary ossification centres and bone is laid down in a similar manner. The nutrient artery enters via the nutrient foramen from a small opening in the diaphysis. It invades the primary centre of ossification, bringing osteogenic cells (osteoblasts on the outside, osteoclasts on the inside.) NOTE: canal of nutrient foramen directed away from growing end when one end grows more than the other. When bone grows same rate at both ends, nutrient artery is horizontal to the bone.)

The Secondary centre

The secondary centres generally appear at the epiphysis. Secondary ossification mostly occurs after birth (except for distal femur and proximal tibia which occurs during foetal development). The epiphyseal arteries and osteogenic cells invade the epiphysis, depositing osteoblasts and osteoclasts which erode the cartilage and build bone. This occurs at both ends of long bones but only one end of digits and ribs.

Evolution[edit]

A spotted gar larva at 22 days stained for cartilage (blue) and bone (red).

Several hypotheses have been proposed for how bone evolved as a structural element in vertebrates. One hypothesis is that bone developed from tissues that evolved to store minerals. Specifically, calcium-based minerals were stored in cartilage and bone was an exaptation development from this calcified cartilage.^[3] However, other possibilities include bony tissue evolving as an osmotic barrier, or as a protective structure.

References[edit]

^ Caetano-Lopes J, Canhão H, Fonseca JE (2007). "Osteoblasts and bone formation". Acta reumatológica portuguesa 32 (2): 103–10. PMID 17572649.
^ ^a ^b Predicting Height from the Length of Limb Bones Part of: Examining Effects of Space Flight on the Skeletal System. Emily Morey-Holton. NASA Ames Research Center. Moffett Field, California
^ Donoghue PC, Sansom IJ (2002). "Origin and early evolution of vertebrate skeletonization". Microsc. Res. Tech. 59 (5): 352–72. doi:10.1002/jemt.10217. PMID 12430166.

Wikimedia Commons has media related to Ossification.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 骨格の正常な発達および骨形成ならびに骨吸収の調節 normal skeletal development and regulation of bone formation and resorption
2. 骨代謝の生理学および生化学的マーカー bone physiology and biochemical markers of bone turnover
3. Cutis verticis gyrata
4. 小児癌患者の骨に関する問題 bone problems in childhood cancer patients
5. 脊椎関節炎の病因 pathogenesis of spondyloarthritis

English Journal

Shell-core bi-layered scaffolds for engineering of vascularized osteon-like structures.

Chen X, Ergun A, Gevgilili H, Ozkan S, Kalyon DM, Wang H.SourceDepartment of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
Biomaterials.Biomaterials.2013 Nov;34(33):8203-12. doi: 10.1016/j.biomaterials.2013.07.035. Epub 2013 Jul 27.
Bottom-up assembly of osteon-like structures into large tissue constructs represents a promising and practical strategy toward the formation of hierarchical cortical bone. Here, a unique two-step approach, i.e., the combination of electrospinning and twin screw extrusion (TSE) techniques was used to
PMID 23896002

Functional role of Runx3 in the regulation of aggrecan expression during cartilage development.

Wigner NA, Soung do Y, Einhorn TA, Drissi H, Gerstenfeld LC.SourceOrthopaedic Research Laboratory, Department of Orthopedic Surgery, Boston University School of Medicine, Boston, Massachusetts; Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts.
Journal of cellular physiology.J Cell Physiol.2013 Nov;228(11):2232-42. doi: 10.1002/jcp.24396.
Runx2 and Runx3 are known to be expressed in the growth plate during endochondral bone formation. Here we addressed the functional role of Runx3 as distinct from Runx2 by using two models of postnatal bone repair: fracture healing that proceeds by an endochondral process and marrow ablation that pro
PMID 23625810

Altered bone development and turnover in transgenic mice over-expressing Lipocalin-2 in bone.

Costa D, Lazzarini E, Canciani B, Giuliani A, Spanò R, Marozzi K, Manescu A, Cancedda R, Tavella S.SourceDipartimento di Medicina Sperimentale, Universita' di Genova & IRCCS AOU San Martino-IST, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
Journal of cellular physiology.J Cell Physiol.2013 Nov;228(11):2210-21. doi: 10.1002/jcp.24391.
Lipocalin-2 (LCN2) is a protein largely expressed in many tissues, associated with different biological phenomena such as cellular differentiation, inflammation and cancer acting as a survival/apoptotic signal. We found that LCN2 was expressed during osteoblast differentiation and we generated trans
PMID 23606520

Japanese Journal

Multifunctional Bone Morphogenetic Protein System in Endocrinology

Otsuka Fumio
Acta Medica Okayama 67(2), 75-86, 2013-04-00
… New biological activities of bone morphogenetic proteins (BMPs) in the endocrine system have recently been revealed. … The BMP system not only induces bone formation but also plays unique tissue-specific roles in various organs. …
NAID 120005232498

Etanercept promotes bone formation via suppression of dickkopf-1 expression in rats with collagen-induced arthritis

Tanida Atsushi,Kishimoto Yuji,Okano Toru,Hagino Hiroshi
Yonago Acta medica 56(1), 13-19, 2013-03-00
NAID 120005263096

Assessment of bone healing and hypoesthesia in the upper lip after Le Fort I osteotomy with self-setting α-tricalcium phosphate and absorbable plates

Ueki Koichiro,Okabe Katsuhiko,Marukawa Kohei,Mukozawa Aya,Moroi Akinori,Miyazaki Mao,Sotobori Megumi,Ishihara Yuri,Yoshizawa Kunio,Ooi Kazuhiro,Kawashiri Shuichi
Journal of Cranio-Maxillofacial Surgery 41(2), 129-134, 2013-03-00
… Purpose: The purpose of this study was to evaluate hypoesthesia of the upper lip and bone formation using self-setting α-tricalcium phosphate (Biopex ®) between the segments following Le Fort I osteotomy with bent absorbable plate fixation. … The area of the Biopex ® after 1 year was significantly smaller than that immediately after surgery (right side: P = 0.0024, left side: P = 0.0001) and bone defects between the segments could not be found in the Biopex ® group. …
NAID 120004419381