collagen matrix

Examples of collagen matrix in the following topics:

• Cartilage Growth

  • Mesenchyme tissue differentiates into chondroblasts and begins secreting the molecules that form the extracellular matrix (ECM).
  • The extracellular matrix consists of ground substance (proteoglycans and glycosaminoglycans) and associated fibers, such as collagen.
  • Remodeling of cartilage is predominantly affected by changes and rearrangements of the collagen matrix, which responds to tensile and compressive forces experienced by the cartilage.
  • Cartilage growth thus mainly refers to matrix deposition, but can include both growth and remodeling of the ECM.
  • Also, because cartilage does not have a blood supply, the deposition of new matrix is slow.

• Development of Joints

  • Chondrification (also known as chondrogenesis) is the process by which cartilage is formed from condensed mesenchyme tissue, which differentiates into chondroblasts and begins secreting the molecules that form the extracellular matrix.
  • Articular cartilage function is dependent on the molecular composition of its extracellular matrix (ECM), which consists mainly of proteoglycans and collagens.
  • Articular cartilage is maintained by embedded chondrocytes that comprise only 1% of the cartilage volume, and remodeling of cartilage is predominantly affected by changes and rearrangements of the collagen matrix, which responds to tensile and compressive forces experienced by the cartilage.
  • Cartilage growth generally refers to matrix deposition, but can include both growth and remodeling of the extracellular matrix.

• Structure, Type, and Location of Cartilage

  • Chondrocytes are first chondroblast cells that produce the collagen extracellular matrix (ECM) and then get caught in the matrix.
  • The remodeling of cartilage is predominantly affected by changes and rearrangements of the collagen matrix, which responds to tensile and compressive forces experienced by the cartilage.
  • This type of cartilage is predominately collagen (yet with few collagen fibers), and its name refers to its glassy appearance.
  • Elastic or yellow cartilage contains elastic fiber networks and collagen fibers.
  • Elastic cartilage is histologically similar to hyaline cartilage but contains many yellow elastic fibers lying in a solid matrix.

• Characteristics of Connective Tissue

  • Together the ground substance and fibers make up the extracellular matrix.
  • Collagen fibers are fibrous proteins and are secreted into the extracellular space and they provide high tensile strength to the matrix.
  • Elastic fibers are long, thin fibers that form branching network in the extracellular matrix.
  • Reticular fibers are short, fine collagenous fibers that can branch extensively to form a delicate network.
  • Collagen fibers are the strongest and most abundant of all the connective tissue fibers.

• Basement Membranes and Diseases

  • The lamina reticularis is attached to the basal lamina with anchoring fibrils (type VII collagen fibers ) and microfibrils (fibrillin).
  • In addition to collagen, this supportive matrix contains intrinsic macromolecular components.
  • This is achieved by cell-matrix adhesions through substrate adhesion molecules (SAMs).
  • Goodpasture disease is the result of an autoimmune response directed at Collagen type IV alpha-3-binding protein, resulting in damage to the lungs and kidneys, bleeding and kidney failure.
  • Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of vertebrates.

• Microscopic Anatomy of Bone

  • Bones are composed of bone matrix, which has both organic and inorganic components.
  • Bone matrix is laid down by osteoblasts as collagen, also known as osteoid.
  • The criss-cross appearance of the fibrous matrix is why it is referred to as woven.
  • The regular parallel alignment of collagen into sheets, or, lamellae, causes lamellar bone to be mechanically strong.
  • Woven bone is characterized by the irregular organization of collagen fibers and is mechanically weak.

• Postnatal Bone Growth

  • Osteoblasts produce a matrix of osteoid that is composed mainly of Type I collagen.
  • Osteoblasts are also responsible for the mineralization of this matrix.
  • Osteoblasts produce bone matrix and mineral, and osteoclasts break down the tissue.
  • The walls of the matrix between the lacunae become very thin.
  • Zone of calcification: The region where the cartilagenous matrix begins to calcify.

• Structural Elements of Connective Tissue

  • The fibroblast is the most common cell which creates collagen.
  • The tropocollagen or collagen molecule is a subunit of larger collagen aggregates such as fibrils.
  • Elastic fibers (or yellow fibers) are bundles of proteins (elastin) found in extracellular matrix of connective tissue and produced by fibroblasts and smooth muscle cells in arteries.
  • Model of the collagen triple helix.
  • The tropocollagen or collagen molecule is a subunit of larger collagen aggregates such as fibrils.

• Deep Wound Healing

  • Therefore, proper reconstitution of the epidermis is often only seen at the edge of the wound, with fibrous scar tissue—formed from the extracellular matrix (ECM) deposited during the proliferative phase—covering the rest of the wound site.
  • The provisional ECM laid down during the proliferative phase is rich in fibronectin and collagen III that combine to allow quicker cell movement through the wound, which is very important during wound healing.
  • However, the ECM of mature skin is rich in collagen I.
  • In large, deep wounds the remodelling of a fibronectin and collagen III-rich ECM to a collagen-I rich ECM may not occur, leading to a weakening of the tissue.

• Hemidesmosomes

  • Hemidesmosomes are asymmetrical and connect the basal face of the expressing cell to the extracellular matrix or to other cells.
  • While desmosomes link two cells together, hemidesmosomes attach one cell to the extracellular matrix.
  • The integrin might then attach to one of many multi-adhesive proteins such as laminin, resident within the extracellular matrix, thereby forming one of many potential adhesions between cell and matrix.
  • The length of these loops may enable them to link or encircle dermal collagen fibers or other components such as those of the elastic microfibril network.