epidermis (vertebrates)
The epidermis (about Greek epi, on; derma skin ) is the epidermis in vertebrates and humans. It forms the outermost layer of skin the actual protective sheath against the environment. From the inside out we distinguish five epidermal layers: basal layer (stratum basale), (stratum spinosum) prickle cell layer, granular layer (stratum granulosum), clear layer (stratum lucidum) and horny layer (stratum corneum). The epidermis consists of 90 percent from keratinocytes, which are held together by desmosomes. In the outer It consists of layers of keratinized squamous cells.
basal
The basal stratum - the "basal" - serves as a single layer innermost cell layer of the regeneration of the skin, instead of here refers to cell division. One daughter cell begins its migration to the surface, the other remains and is divided again. The nutrient supply is still relatively good because the epidermis contains no blood vessels. The delimitation of the underlying dermis is the same as in all epithelial cells through a basement membrane, the skin is mostly flat in the fields runs, is strong in the groin skin but deformed by papillae (projections of the dermis), the density dictates the structure of the dermal ridges.
lie within the basal cell layer of special cells for purposes of sensation of touch, the Merkel cells. In addition, here are melanocytes, the pigment-producing cells.
stratum spinosum
In what is also called "prickle cell layer," stratum spinosum cells by Zytoplasmaausläufer associated with desmosomes. Here begins the called keratinization, gradual cornification. As the cells shrink during histological processing, they have in preparation a prickly appearance. In the stratum spinosum are also immune cells of the lymphatic system, known as Langerhans cells.
stratum basale and stratum spinosum are summarized as stratum germinative (synonym: germ layer, regeneration layer) refers.
0 comments:
Post a Comment