extracellular matrix

Examples of extracellular matrix in the following topics:

• Extracellular Matrix of Animal Cells

  • The extracellular matrix of animal cells holds cells together to form a tissue and allow tissues to communicate with each other.
  • Collectively, these materials are called the extracellular matrix .
  • Not only does the extracellular matrix hold the cells together to form a tissue, but it also allows the cells within the tissue to communicate with each other.
  • An example of the role of the extracellular matrix in cell communication can be seen in blood clotting.
  • The extracellular matrix consists of a network of proteins and carbohydrates.

• 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.
  • Thin, extracellular, electron-dense lines, parallel to the plasma membrane, subjacent to the outer plaque are visible in one third of HDs and are termed sub-basal dense plates (SBDPs).

• Characteristics of Connective Tissue

  • Together the ground substance and fibers make up the extracellular matrix.
  • It is composed of proteoglycans and cell adhesion proteins that allow the connective tissue to act as glue for the cells to attach to the 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.
  • Connective tissues consist of three parts: cells suspended in a ground substance or matrix; and most have fibers running through it.

• 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.

• Cell Signaling and Cell Death

  • For example, most normal animal cells have receptors that interact with the extracellular matrix, a network of glycoproteins that provides structural support for cells in an organism.
  • The binding of cellular receptors to the extracellular matrix initiates a signaling cascade within the cell.
  • However, if the cell moves away from the extracellular matrix, the signaling ceases, and the cell undergoes apoptosis.

• 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.
  • The chondroblasts then trap themselves in lacunae, small spaces that are no longer in contact with the newly created matrix and contain extracellular fluid.
  • 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.

• Exocytosis

  • Exocytosis is the process by which cells release particles from within the cell into the extracellular space.
  • Exocytosis' main purpose is to expel material from the cell into the extracellular fluid; this is the opposite of what occurs in endocytosis.
  • This fusion opens the membranous envelope on the exterior of the cell and the waste material is expelled into the extracellular space .
  • Some examples of cells releasing molecules via exocytosis include the secretion of proteins of the extracellular matrix and secretion of neurotransmitters into the synaptic cleft by synaptic vesicles.

• Biofilms

  • These cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS).
  • Biofilm EPS, also referred to as slime, is a polymeric conglomeration composed of extracellular DNA, proteins, and polysaccharides.
  • Enzymes that degrade the biofilm extracellular matrix, such as dispersin B and deoxyribonuclease, may play a role in biofilm dispersal.
  • Biofilm matrix-degrading enzymes may be useful as anti-biofilm agents.
  • One benefit of this environment is increased resistance to detergents and antibiotics, as the dense extracellular matrix and the outer layer of cells protect the interior of the community.

• Fluid Compartments

  • For example, the mitochondrial matrix separates the mitochondrion into compartments.
  • Extracellular fluid (ECF) or extracellular fluid volume (ECFV) usually denotes all body fluid outside of cells.
  • The extracellular fluid also includes the transcellular fluid; making up only about 2.5% of the ECF.
  • The pH of extracellular fluid is tightly regulated by buffers and maintained around 7.4.
  • It is the intravascular fluid part of extracellular fluid (all body fluid outside of cells).

• Extracellular Immune Avoidance

  • These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS).
  • Biofilm EPS, which is also referred to as slime, is a polymeric conglomeration generally composed of extracellular DNA, proteins, and polysaccharides.