Everything about The Basement Membrane totally explained
The
basement membrane is a structure that supports overlying
epithelial or
endothelial cells.
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 0.1–2
micrometers in thickness. This type III collagen is of the reticular type, in contrast to the fibrillar collagen found in the
interstitial matrix. 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) coats these fibers and they're high in
heparan sulfate) and the Lamina Lucida (made up of
laminin,
integrins,
entactins, and
dystroglycans) together make up the
basal lamina. Lamina Reticularis attached to basal lamina with anchoring fibrils (type VII collagen fibers) and
microfibrils (fibrilin) is collectively known as the basement membrane.
Function and importance
The primary function of the basement membrane is to anchor down the
epithelium to its loose connective tissue underneath. This is achieved by cell-
matrix adhesions through
cell adhesion molecules (CAMs).
The basement membrane acts as a mechanical barrier, preventing
malignant cells from invading the deeper tissues. Early stages of malignancy that are thus limited to the epithelial layer by the basement membrane are called
carcinoma in situ.
The basement membrane is also essential for
angiogenesis (development of new blood vessels). Basement membrane proteins have been found to accelerate
differentiation of
endothelial cells.
It also plays an important role in
glomerular filtration in the
kidney.
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.
Further Information
Get more info on 'Basement Membrane'.
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