Parts of this article (those related to PMID 24292720) need to be updated. Please help update this article to reflect recent events or newly available information.(October 2017)
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 necessarily vice versa.
The exact mechanisms by which bone development is triggered remains unclear, but growth factors and cytokines appear to play a role.
In long bones, bone tissue first appears in the diaphysis (middle of shaft). Chondrocytes multiply and form trebeculae. Cartilage is progressively eroded and replaced by hardened bone, extending towards the epiphysis. A perichondrium layer surrounding the cartilage forms the periosteum, which generates osteogenic cells that then go on to make a collar that encircles the outside of the bone and remodels the medullary cavity on the inside.
The nutrient artery enters via the nutrient foramen from a small opening in the diaphysis. It invades the primary center of ossification, bringing osteogenic cells (osteoblasts on the outside, osteoclasts on the inside.) The canal of the nutrient foramen is directed away from more active end of bone when one end grows more than the other. When bone grows at same rate at both ends, the nutrient artery is perpendicular to the bone.
Most other bones (e.g. vertebrae) also have primary ossification centers, and bone is laid down in a similar manner.
Secondary centers
The secondary centers generally appear at the epiphysis. Secondary ossification mostly occurs after birth (except for distal femur and proximal tibia which occurs during 9th month of fetal development). The epiphyseal arteries and osteogenic cells invade the epiphysis, depositing osteoclasts and osteoblasts which erode the cartilage and build bone, respectively. This occurs at both ends of long bones but only one end of digits and ribs.
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.[4] However, other possibilities include bony tissue evolving as an osmotic barrier, or as a protective structure.
See alsoedit
Look up ossification in Wiktionary, the free dictionary.
Fibrodysplasia ossificans progressiva, an extremely rare genetic disease which causes fibrous tissue (muscle, tendon, ligament etc.) to ossify when damaged
Primrose syndrome, a rare genetic disease in which cartilage becomes ossified.
Referencesedit
Wikimedia Commons has media related to Ossification.
^Caetano-Lopes J, Canhão H, Fonseca JE (2007). "Osteoblasts and bone formation". Acta reumatológica portuguesa. 32 (2): 103–10. PMID 17572649.
^ abEmily Morey-Holton. . Examining Effects of Space Flight on the Skeletal System. Moffett Field, California: NASA Ames Research Center. Archived from the original on 2012-03-01.
^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. S2CID 10933086.
December 20, 2023
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This article is about the biological process For the concept in computer networking see Protocol ossification This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Ossification news newspapers books scholar JSTOR May 2011 Learn how and when to remove this template message Parts of this article those related to PMID 24292720 need to be updated Please help update this article to reflect recent events or newly available information October 2017 Learn how and when to remove this template message Ossification also called osteogenesis or bone mineralization in bone remodeling is the process of laying down new bone material by cells named osteoblasts It is synonymous with bone tissue formation 1 There are two processes resulting in the formation of normal healthy bone tissue 2 Intramembranous ossification is the direct laying down of bone into the primitive connective tissue mesenchyme while endochondral ossification involves cartilage as a precursor Bone is broken down by osteoclasts and rebuilt by osteoblasts both of which communicate through cytokine TGF b IGF signalling 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 internal fixation with metal plates screws pins rods and nails 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 necessarily vice versa The exact mechanisms by which bone development is triggered remains unclear but growth factors and cytokines appear to play a role Time period 3 Bones affected 3 Third month of fetal development Ossification in long bones beginningFourth month Most primary ossification centers have appeared in the diaphyses of bone Birth to 5 years Secondary ossification centers appear in the epiphyses5 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 ossified18 to 23 years Bone of the lower limbs and os coxae become completely ossified23 to 26 years Bone of the sternum clavicles and vertebrae become completely ossifiedBy 25 years Nearly all bones are completely ossifiedContents 1 Intramembranous ossification 2 Endochondral ossification 3 Evolution 4 See also 5 ReferencesIntramembranous ossification editThis section needs expansion You can help by adding to it January 2021 Intramembranous ossification forms the flat bones of the skull mandible and hip bone Endochondral ossification edit nbsp Diagram showing stages of endochondral ossificationEndochondral ossification is the formation of long bones and other bones This requires a hyaline cartilage precursor There are two centers of ossification for endochondral ossification The primary centerIn long bones bone tissue first appears in the diaphysis middle of shaft Chondrocytes multiply and form trebeculae Cartilage is progressively eroded and replaced by hardened bone extending towards the epiphysis A perichondrium layer surrounding the cartilage forms the periosteum which generates osteogenic cells that then go on to make a collar that encircles the outside of the bone and remodels the medullary cavity on the inside The nutrient artery enters via the nutrient foramen from a small opening in the diaphysis It invades the primary center of ossification bringing osteogenic cells osteoblasts on the outside osteoclasts on the inside The canal of the nutrient foramen is directed away from more active end of bone when one end grows more than the other When bone grows at same rate at both ends the nutrient artery is perpendicular to the bone Most other bones e g vertebrae also have primary ossification centers and bone is laid down in a similar manner Secondary centersThe secondary centers generally appear at the epiphysis Secondary ossification mostly occurs after birth except for distal femur and proximal tibia which occurs during 9th month of fetal development The epiphyseal arteries and osteogenic cells invade the epiphysis depositing osteoclasts and osteoblasts which erode the cartilage and build bone respectively This occurs at both ends of long bones but only one end of digits and ribs nbsp Microscopic image of the growth plateEvolution edit nbsp 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 4 However other possibilities include bony tissue evolving as an osmotic barrier or as a protective structure See also edit nbsp Look up ossification in Wiktionary the free dictionary Dystrophic calcification Mechanostat a model describing ossification and bone loss Ossicone the horn like or antler like protuberances on the heads of giraffes and related species Osteogenesis imperfecta a juvenile bone disease Fibrodysplasia ossificans progressiva an extremely rare genetic disease which causes fibrous tissue muscle tendon ligament etc to ossify when damaged Primrose syndrome a rare genetic disease in which cartilage becomes ossified References edit nbsp Wikimedia Commons has media related to Ossification bone formation Definition amp Physiology Encyclopedia Britannica Retrieved 2021 01 22 Caetano Lopes J Canhao H Fonseca JE 2007 Osteoblasts and bone formation Acta reumatologica portuguesa 32 2 103 10 PMID 17572649 a b Emily Morey Holton Predicting Height from the Length of Limb Bones Examining Effects of Space Flight on the Skeletal System Moffett Field California NASA Ames Research Center Archived from the original on 2012 03 01 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 S2CID 10933086 Retrieved from https en wikipedia org w index php title Ossification amp oldid 1187128548, wikipedia, wiki, book, books, library,
