Electron micrograph showing basal lamina lining the outer surface of the cell membrane. The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer

The basal lamina is a layer of extracellular matrix on which epithelium sits and which is secreted by the epithelial cells. In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body It is often confused with the basement membrane, and sometimes used inconsistently in the literature, see below. The basement membrane is a structure that supports overlying Epithelial or Endothelial cells.

It is typically about 40-50 nanometres thick (with exceptions such as the basal laminae that compose the 100-200 nanometre thick glomerular basement membrane). A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a The glomerular basement membrane is the Basal laminal portion of the Glomerulus which performs the actual filtration though the filtration slits between the Podocytes

Layers

The layers of the basal lamina ("BL") and those of the basement membrane ("BM") are described below:

Anchoring fibers composed of type VII collagen extend from the basal lamina into the underlying reticular lamina and loop around collagen bundles. Anchoring fibrils (composed largely of type VII Collagen) extend from the Basal lamina of Epithelial cells and attach to the lamina reticularis (also known Although found beneath all basal laminae, they are especially numerous in stratified squamous cells of the skin. In Anatomy, squamous epithelium (from Latin squama, "scale" is an Epithelium characterised by its most superficial layer consisting

These layers should not be confused with the lamina propria, which is found outside the basal lamina. The lamina propria is a constituent of the moist linings known as mucous membranes or Mucosa, which line various tubes in the body (such as the respiratory tract the gastrointestinal ^[5]

Basal lamina vs. basement membrane

The term "basal lamina" is usually used with electron microscopy, while the term "basement membrane" is usually used with light microscopy. An electron microscope is a type of Microscope that uses Electrons to illuminate a specimen and create an enlarged image Microscopy is the technical field of using microscopes to view samples or objects The structure known as the basement membrane in light microscopy refers to the stained structure anchoring an epithelial layer. This encompasses the basal lamina secreted by epithelial cells and typically a reticular lamina secreted by other cells.

The basal lamina cannot be distinguished under the light microscope, but under the higher magnification of an electron microscope, the basal lamina and lamina reticularis are visibly distinct structures.

Some theorize that the lamina lucida is an artifact created when preparing the tissue, and that the basement membrane is therefore equal to the lamina densa in vivo. In vivo ( Latin: within the living means that which takes place inside an organism. ^[6]

Examples of basement membranes include:

• Basilar membrane
• Bruch's membrane
• Descemet's membrane
• Glomerular basement membrane

See also

• Alveolar-capillary barrier
• Basolateral membrane
• Collagen
• Glomerular basement membrane
• Lamina propria

References

1. ^ Histology at BU 22403loa
2. ^ UIUC Histology Subject 500
3. ^ UIUC Histology Subject 499
4. ^ Histology at BU 20904loa
5. ^ Histology at BU 22203loa
6. ^ Chan F, Inoue S (1994). The basilar membrane within the Cochlea of the Inner ear is a stiff structural element that separates two liquid-filled tubes that run along the coil of the cochlea Bruch's membrane is the innermost layer of the Choroid. It is also called the vitreous lamina, because of its glassy microscopic appearance Descemet's membrane is the Basement membrane that lies between the corneal proper substance also called stroma and the endothelial layer of the Cornea The glomerular basement membrane is the Basal laminal portion of the Glomerulus which performs the actual filtration though the filtration slits between the Podocytes The alveolar-capillary barrier (or membrane, or blood-air barrier) exists in the gas exchanging region of the Lungs. 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 The glomerular basement membrane is the Basal laminal portion of the Glomerulus which performs the actual filtration though the filtration slits between the Podocytes The lamina propria is a constituent of the moist linings known as mucous membranes or Mucosa, which line various tubes in the body (such as the respiratory tract the gastrointestinal For similarly-named academic institutions see Education in Boston MA. The College of Medicine at Urbana-Champaign is a medical school at the University of Illinois at Urbana-Champaign. The College of Medicine at Urbana-Champaign is a medical school at the University of Illinois at Urbana-Champaign. For similarly-named academic institutions see Education in Boston MA. For similarly-named academic institutions see Education in Boston MA. "Lamina lucida of basement membrane: an artefact. ". Microsc Res Tech 28 (1): 48-59. doi:10.1002/jemt.1070280106. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 8061357.  

• 1 Kierszenbaum, AL. Histology and Cell Biology: An Introduction to Pathology. Mosby, Inc, MO: 2002. Chapter 4.