bone formation

also called  ossification 

      process by which new bone is produced. Ossification begins about the third month of fetal life in humans and is completed by late adolescence. The process takes two general forms, one for compact bone, which makes up roughly 80 percent of the skeleton, and the other for cancellous bone, including parts of the skull, the shoulder blades, and the ends of the long bones.

      Bone of the first type begins in the embryonic skeleton with a cartilage model, which is gradually replaced by bone. Specialized connective tissue cells called osteoblasts (osteoblast) secrete a matrix material called osteoid, a gelatinous substance made up of collagen, a fibrous protein, and mucopolysaccharide, an organic glue. Soon after the osteoid is laid down, inorganic salts are deposited in it to form the hardened material recognized as mineralized bone. The cartilage cells die out and are replaced by osteoblasts clustered in ossification centres. Bone formation proceeds outward from these centres. This replacement of cartilage by bone is known as endochondral ossification. Most short bones have a single ossification centre near the middle of the bone; long bones of the arms and legs typically have three, one at the centre of the bone and one at each end. Ossification of long bones proceeds until only a thin strip of cartilage remains at either end; this cartilage, called the epiphyseal plate, persists until the bone reaches its full adult length and is then replaced with bone.

      The flat bones of the skull are not preformed in cartilage like compact bone but begin as fibrous membranes consisting largely of collagen and blood vessels. Osteoblasts secrete the osteoid into this membrane to form a spongelike network of bony processes called trabeculae. The new bone formation radiates outward from ossification centres in the membrane. This process is called intermembranous ossification. There are several ossification centres in the skull. At birth, bone formation is incomplete, and soft spots can be felt between these centres. The lines where the new bone from adjacent centres meets form cranial sutures visible on the surface of the adult skull.

      Both endochondral and intermembranous ossification produce immature bone, which undergoes a process of bone resorption and deposition called bone remodeling to produce mature bone.

* * *


Universalium. 2010.

Look at other dictionaries:

  • Bone healing — or fracture healing is a proliferative physiological process, in which the body facilitates repair of bone fractures. Physiology and process of healing In the process of fracture healing, several phases of recovery facilitate the proliferation… …   Wikipedia

  • Bone morphogenetic protein 2 — PDB rendering based on 3bmp. Av …   Wikipedia

  • Bone morphogenetic protein 1 — (BMP1) is a protein that belongs to the peptidase M12A family of proteins. It induces bone and cartilage development. It is unlike other bone morphogenetic proteins since it does not belong to the TGFβ superfamily of proteins. It was initially… …   Wikipedia

  • Bone morphogenetic protein — Bone Morphogenetic Proteins (BMPs) are a group of growth factors and cytokines known for their ability to induce the formation of bone and cartilage. TypesOriginally, seven such proteins were discovered. Of these, six (BMP2 through BMP7) belong… …   Wikipedia

  • Bone morphogenetic protein 4 — Bone morphogenetic protein 4, also known as BMP4, is a human gene. PBB Summary section title = summary text = The protein encoded by this gene is a member of the bone morphogenetic protein family which is part of the transforming growth factor… …   Wikipedia

  • Bone resorption — is the process by which osteoclasts break down bone [MeshName|Bone+Resorption] and release the minerals, resulting in a transfer of calcium from bone fluid to the blood. The osteoclasts are multi nucleated cells that contain numerous mitochondria …   Wikipedia

  • Bone remodeling — is a life long process where old bone is removed from the skeleton (a sub process called bone resorption) and new bone is added (a sub process called bone formation). These processes also control the reshaping or replacement of bone during growth …   Wikipedia

  • Bone morphogenetic protein 6 — Bone morphogenetic protein 6, also known as BMP6, is a human gene.cite web | title = Entrez Gene: BMP6 bone morphogenetic protein 6| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=654| accessdate = ] The… …   Wikipedia

  • Bone morphogenetic protein 3 — (osteogenic), also known as BMP3 or osteogenin, is a human gene.cite web | title = Entrez Gene: BMP3 bone morphogenetic protein 3 (osteogenic)| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=651| accessdate …   Wikipedia

  • bone — /bohn/, n., v., boned, boning, adv. n. 1. Anat., Zool. a. one of the structures composing the skeleton of a vertebrate. b. the hard connective tissue forming the substance of the skeleton of most vertebrates, composed of a collagen rich organic… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.