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Lamina Densa
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) dermal microfibrils.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology'' (10th ed.). Saunders. Page 5-6. . See also * Basal lamina References Skin anatomy {{Dermatology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basement Membrane
The basement membrane is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between epithelial tissues including mesothelium and endothelium, and the underlying connective tissue. Structure As seen with the electron microscope, the basement membrane is composed of two layers, the basal lamina and the reticular lamina. The underlying connective tissue attaches to the basal lamina with collagen VII anchoring fibrils and fibrillin microfibrils. 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. The electron-dense lamina densa layer is about 30–70 nanometers thick and consists of an underlying network of reticular col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epidermis (skin)
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water released from the body into the atmosphere through transepidermal water loss. The epidermis is composed of multiple layers of flattened cells that overlie a base layer ( stratum basale) composed of columnar cells arranged perpendicularly. The layers of cells develop from stem cells in the basal layer. The human epidermis is a familiar example of epithelium, particularly a stratified squamous epithelium. The word epidermis is derived through Latin , itself and . Something related to or part of the epidermis is termed epidermal. Structure Cellular components The epidermis primarily consists of keratinocytes ( proliferating basal and differentiated suprabasal), which comprise 90% of its cells, but also contains melanocytes, Langerha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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). It is a roughly 40 nanometre wide electron-lucent zone between the plasma membrane of the basal cells and the (electron-dense) lamina densa of the basement membrane.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology'' (10th ed.). Saunders. Page 5. . 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. However, unlike the lamina densa, the electron-dense zone adjacent to enamel show no signs of hemidesmosomes. Some theorize that the lamina lucida is an artifact created when preparing the tissue, and that the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basal Lamina
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. The basal lamina is visible only with the electron microscope, where it appears as an electron-dense layer that is 20–100 nm thick (with some exceptions that are thicker, such as basal lamina in lung alveoli and renal glomeruli). Structure The layers of the basal lamina ("BL") and those of the basement membrane ("BM") are described below: Anchoring fibrils composed of type VII collagen extend from the basal lamina into the underlying reticular lamina and loop around collagen bundles. Although found beneath all basal laminae, they are especially numerous in stratified squamous cells of the skin. These layers should not be confused with the lamina propria, which is found outside the basal lamina. Basement membrane The basement membran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
