What is lamina lucida and lamina densa?
The basal lamina layer can further be subdivided into two layers based on their visual appearance in electron microscopy. The lighter-colored layer closer to the epithelium is called the lamina lucida, while the denser-colored layer closer to the connective tissue is called the lamina densa.
What is lamina lucida?
The lamina lucida is a component of the basement membrane which is found between the epithelium and underlying connective tissue (e.g., epidermis and dermis of the skin). Similarly, electron-lucent and electron-dense zones can be seen between enamel of teeth and the junctional epithelium.
What is the function of lamina lucida?
Laminin is a large (Mr = 1,000,000) noncollagenous glycoprotein with chains of 200,000 and 400,000 daltons. It has been localized to the basement membrane lamina lucida and functions to bind epithelial cells to the basement membrane. A heparan sulfate proteoglycan has also been identified in the basement membrane.
What’s the difference between basal lamina and basement membrane?
The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, though it does constitute a portion of the basement membrane.
What is the lamina densa made up of?
collagen
The lamina densa consists of nonfibrilar collagen, in particular collagen IV, glycoproteins such as laminin, perlecan and nidogen, and proteoglycans. The reticular layer consists of collagens, including type III, and it consists of fibronectin, which are embedded in an amorphous proteoglycan-rich ground substance.
What is lamina made of?
The basal lamina consists of a mixture of collagens, laminin (glycoprotein), perlecan (heparan sulphate glycoprotein), entactin (glycoprotein). These proteins can bind to each other to make a highly crosslinked extracellular matrix as shown in this diagram.
Is basement membrane connective tissue?
Basement membranes are thin sheet-like extracellular structures that form an anatomical barrier wherever cells meet connective tissues. They provide a substrate for organs and cells and relay important signals for the development of organs and for differentiation and maintenance of the tissue.
Where is the lamina densa located?
The lamina densa is a component of the basement membrane zone between the epidermis and dermis of the skin, and is an electron-dense zone between the lamina lucida and dermis, synthesized by the basal cells of the epidermis, and composed of (1) type IV collagen, (2) anchoring fibrils made of type VII collagen, and (3) …
Is basal lamina thicker than basement membrane?
The strength of this connection is important for development and growth. Many textbooks do not distinguish between the basal lamina as described and the basement membrane, a thicker layer which includes the basal lamina and extracellular components of the underlying connective-tissue matrix.
What is the basement membrane in the kidney?
The glomerular basement membrane of the kidney is the basal lamina layer of the glomerulus.
Where is the lamina lucida located in the body?
The lamina lucida is a component of the basement membrane which is found between the epithelium and underlying connective tissue (e.g., epidermis and dermis of the skin).
Is the Great Dane at risk for lamina lucida?
Great Danes appear to be at a greater risk than other breeds. Lesion is deeper in the skin since the anchoring fibrils (type VII collagen) of the lamina densa are the target antigen. Direct smears are negative for acantholytic cells because this disease does not affect intercellular adhesion.
What is the structure of the reticular lamina?
The reticular lamina lies beneath the basal lamina and is composed of loose connective tissue with type III collagen fibrils. Anchoring fibrils extend from the lamina densa and loop around the type III collagen fibrils serving to attach the basal lamina to the underlying loose connective tissue of the reticular lamina. Capillary 45,000x.
Is the junctional epithelium part of the lamina lucida?
Similarly, electron-lucent and electron-dense zones can be seen between enamel of teeth and the junctional epithelium. The electron-lucent zone is adjacent to the cells of the junctional epithelium and might be considered a continuation of the lamina lucida as both are seen to harbour hemidesmosomes.