Cartilage

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Growth and development

Main article: Chondrogenesis

In embryogenesis, the skeletal system is derived from the mesoderm germ layer. Chondrification (also known as chondrogenesis) is the process by which cartilage is formed from condensed mesenchyme tissue, which differentiates into chondrocytes and begins secreting the molecules that form the extracellular matrix: rovolution. ground venison

Skeletal blast cells that express the Sox9 transcription factor, followed by continued expression of Sox5 and Sox6, develop into chondroblast precursors, while those that express Runx2, followed by osterix develop into osteogenic precursors. The condroblastic differentiation is favored in regions under compressive forces and low pO2 because these downregulate BMP3, which normally inhibits cartilage differentiation. Osteogenic differentiation is favored under neutral or mild, intermittent tensile forces and relatively high pO2, which leads to upregulation of BMP4. High tensile strength favors the formation of tendinous connective tissue. popcorn popper

Diseases and treatment pure cocoa powder

Main article: Chondropathy

There are several diseases which can affect the cartilage. Chondrodystrophies are a group of diseases characterized by disturbance of growth and subsequent ossification of cartilage. Some common diseases affecting/involving the cartilage are listed below.

Osteoarthritis: The cartilage covering bones (articular cartilage) is thinned, eventually completely worn out, resulting in a "bone against bone" joint, reduced motion and pain. Ost, affects the joints exposed to high stress and is therefore considered the result of "wear and tear" rather than a true disease. It is treated by Arthroplasty, the replacement of the joint by a synthetic joint often made of a Stainless Steel alloy (cobalt chromoly) and High Molecular Weight Polyethylene (HMWPE). Chondroitin sulfate, a monomer of the polysaccharide portion of proteoglycan, has been shown to reduce the symptoms of osteoarthritis, possibly by increasing the synthesis of the extracellular matrix.

Traumatic rupture or detachment: The cartilage in the knee is frequently damaged, and can be partially repaired through knee cartilage replacement therapy

Achondroplasia: Reduced proliferation of chondrocytes in the epiphyseal plate of long bones during infancy and childhood, resulting in dwarfism.

Costochondritis: Inflammation of cartilage in the ribs, causing chest pain.

Spinal disc herniation : Asymmetrical compression of an intervertebral disc ruptures the sac-like disc, causing a herniation of its soft content. The hernia often compresses the adjacent nerves and causes back pain.

Relapsing polychondritis: a destruction, probably autoimmune, of cartilage, especially of the nose and ears, causing disfiguration. Death occurs by suffocation as the larynx loses its rigidity and collapses.

Tumors made up of cartilage tissue, either benign or malignant, can occur. They usually appear in bone, rarely in pre-existing cartilage. The benign tumors are called chondroma, the malignant ones chondrosarcoma. Tumors arising from other tissues may also produce a cartilage-like matrix, the best known being pleomorphic adenoma of the salivary glands.

The matrix of cartilage acts as a barrier, preventing the entry of lymphocytes or diffusion of immunoglobulins. This property allows for the transplantation of cartilage from one individual to another without fear of tissue rejection.

Repair

Cartilage has limited repair capabilities, because chondrocytes are bound in lacunae, they cannot migrate to damaged areas. Therefore if damaged, it is difficult to heal. Also, because hyaline cartilage does not have a blood supply, the deposition of new matrix is slow. Damaged hyaline cartilage is usually replaced by fibrocartilage scar tissue. Over the last years, surgeons and scientists have elaborated a series of cartilage repair procedures that help to postpone the need for joint replacement.

Bioengineering techniques are being developed to generate new cartilage, using a cellular "scaffolding" material and cultured cells to grow artificial cartilage.

Cartilage in animals

Cartilaginous fish

Cartilaginous fish (chondrichthyes) like sharks, rays and skates have a skeleton composed entirely of cartilage. Shark cartilage is a popular but unproven dietary supplement.

Invertebrate cartilage

Cartilage tissue can also be found among invertebrates such as horseshoe crabs, marine snails, and cephalopods.

See also

Biomechanics

References

^ Salentijn, L. Biology of Mineralized Tissues: Cartilage and Bone, Columbia University College of Dental Medicine post-graduate dental lecture series, 2007

^ International Cartilage Repair Society ICRS

General references

Keller-Peck, C. (2008). Vertebrate Histology, ZOOL 400. Boise State University. 

External links

KUMC.edu, Cartilage tutorial, University of Kansas Medical Center

Bartleby.com, text from Gray's anatomy

MadSci.org, I've heard 'Ears and nose do not ever stop growing.' Is this false?

CartilageHealth.com, Information on Articular Cartilage Injury Prevention, Repair and Rehabilitation

Cartilage.org, International Cartilage Repair Society

v  d  e

Musculoskeletal system  connective tissue: bone and cartilage (TA A02.0  GA 2.86-95)

Cartilage

perichondrium  fibrocartilage callus  metaphysis

cells (chondroblast  chondrocyte)

types (hyaline  elastic  fibrous)

Bone

Ossification

intramembranous  endochondral

Cycle

osteoblast  osteoid  osteocyte  osteoclast

Types

cancellous  cortical

Regions

subchondral bone  epiphysis  epiphyseal plate/metaphysis  diaphysis  Condyle  Epicondyle

Structure

osteon / Haversian system  Haversian canals  Volkmann's canals  connective tissue (endosteum  periosteum)  Sharpey's fibres  enthesis  lacunae  canaliculi  trabeculae  medullary cavity  bone marrow

Shapes

long  short  flat  irregular  sesamoid

Bone and cartilage navboxes: anat / physio / dev, noncongen / congen / neoplasia, symptoms+signs / eponymous signs, proc

Categories: Skeletal system | Tissues