Illustration depicting basement membrane in relation to epithelium and endothelium. In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body The endothelium is the thin layer of cells that line the interior surface of Blood vessels forming an interface between circulating Blood in the Also seen are other extracellular matrix components

The basement membrane is a structure that supports overlying epithelial or endothelial cells. In Biology, the extracellular matrix ( ECM) is the Extracellular part of animal tissue that usually provides structural support to the cells In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body The endothelium is the thin layer of cells that line the interior surface of Blood vessels forming an interface between circulating Blood in the

Composition

The basement membrane consists of an electron-dense membrane called the lamina densa, about 30–70 nanometers in thickness, and an underlying network of reticular collagen (type III) fibrils (its precursor is fibroblasts) which average 30 nanometers in diameter and 0. The basal lamina is a layer of extracellular matrix on which Epithelium sits and which is secreted by the epithelial cells A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a Collagen is the main Protein of Connective tissue in Animals and the most abundant protein in Mammals making up about 50% of the whole-body protein 1–2 micrometers in thickness. A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre This type III collagen is of the reticular type, in contrast to the fibrillar collagen found in the interstitial matrix. ^[1][2] In addition to collagen, this supportive matrix contains intrinsic macromolecular components.

The Lamina Densa (which is made up of type IV collagen fibers; perlecan (a heparan sulfate proteoglycan)^[3] coats these fibers and they are high in heparan sulfate) and the Lamina Lucida (made up of laminin, integrins, entactins, and dystroglycans) together make up the basal lamina. Heparan sulfate (HS is a linear Polysaccharide found in all animal tissues Laminin is the major non-collagenous component of the Basal lamina, such as those on which cells of an Epithelium sit Integrins are Cell surface receptors that interact with the Extracellular matrix (ECM and mediate various intracellular signals. Entactin (or nidogen) is a component of the Basement membrane alongside other components such as Collagen type IV Proteoglycans ( heparan sulfate Dystroglycan 1 (dystrophin-associated glycoprotein 1, also known The basal lamina is a layer of extracellular matrix on which Epithelium sits and which is secreted by the epithelial cells Lamina Reticularis attached to basal lamina with anchoring fibrils (type VII collagen fibers) and microfibrils (fibrilin) is collectively known as the basement membrane. The microfibril is a very fine Fibril, or fiber-like strand consisting of Glycoproteins. ^[4]

Function and importance

The primary function of the basement membrane is to anchor down the epithelium to its loose connective tissue underneath. In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body This is achieved by cell-matrix adhesions through cell adhesion molecules (CAMs). In Biology, the extracellular matrix ( ECM) is the Extracellular part of animal tissue that usually provides structural support to the cells Cell Adhesion Molecules ( CAM s are Proteins located on the cell surface involved with the Binding with other cells or with the Extracellular

The basement membrane acts as a mechanical barrier, preventing malignant cells from invading the deeper tissues. Malignant (from the Latin roots mal- = "bad" and -genus = "born" is a medical term used to describe a severe and progressively worsening disease ^[5] Early stages of malignancy that are thus limited to the epithelial layer by the basement membrane are called carcinoma in situ. Carcinoma in situ (CIS is an early form of Carcinoma defined by the absence of invasion of surrounding tissues

The basement membrane is also essential for angiogenesis (development of new blood vessels). Angiogenesis is a physiological process involving the growth of new Blood vessels from pre-existing vessels Basement membrane proteins have been found to accelerate differentiation of endothelial cells. The endothelium is the thin layer of cells that line the interior surface of Blood vessels forming an interface between circulating Blood in the ^[6]

It also plays an important role in glomerular filtration in the kidney. Renal function, in Nephrology, is an indication of the state of the Kidney and its role in Renal physiology. The kidneys are complicated organs that have numerous biological roles Basement membrane is non cellular.

Noncollagenous domain basement membrane collagen type IV is autoantigen (target antigen) of autoantibodies in the autoimmune disease Goodpasture's syndrome. ^[7]

See also

intima

References