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7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically converted to vitamin D3 in the skin, therefore functioning as provitamin-D3. The presence of this compound in human skin enables humans to manufacture vitamin D3 (cholecalciferol) from ultraviolet UV-B rays in the sun light, via previtamin D3, an intermediate isomer. It is also found in the milk of several mammalian species. Lanolin, a waxy substance that is naturally secreted by wool-bearing mammals, contains 7-DHC which is converted into vitamin D by sunlight and then ingested during grooming as a nutrient. In insects it is a precursor for the hormone ecdysone, required for reaching adulthood. It was discovered by Nobel-laureate organic chemist Adolf Windaus.
The epidermis is the outermost of the three layers that make up 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 Malpighian layer of the skin is generally defined as both the stratum basale and stratum spinosum as a unit, although it is occasionally defined as the stratum basale specifically, or the stratum spinosum specifically.
The stratum basale is the deepest layer of the five layers of the epidermis, the external covering of skin in mammals.
The lunula, or lunulae (pl.), is the crescent-shaped whitish area of the bed of a fingernail or toenail.
The stratum lucidum is a thin, clear layer of dead skin cells in the epidermis named for its translucent appearance under a microscope. It is readily visible by light microscopy only in areas of thick skin, which are found on the palms of the hands and the soles of the feet.
The stratum spinosum is a layer of the epidermis found between the stratum granulosum and stratum basale. This layer is composed of polyhedral keratinocytes. These are joined together with desmosomes. Their spiny appearance is due to shrinking of the microfilaments between desmosomes that occurs when stained with H&E. Keratinization begins in the stratum spinosum, although the actual keratinocytes begin in the stratum basale. They have large pale-staining nuclei as they are active in synthesizing fibrilar proteins, known as cytokeratin, which build up within the cells aggregating together forming tonofibrils. The tonofibrils go on to form the desmosomes, which allow for strong connections to form between adjacent keratinocytes. The stratum spinosum also contains Langerhans cells.
Panegyrtes is a genus of longhorn beetles of the subfamily Lamiinae, containing the following species:
Panegyrtes crinitus is a species of beetle in the family Cerambycidae. It was described by Galileo and Martins in 1995. It is known from Brazil.
Panegyrtes delicatus is a species of beetle in the family Cerambycidae. It was described by Galileo and Martins in 1995. It is known from Brazil.
Panegyrtes fraternus is a species of beetle in the family Cerambycidae. It was described by Galileo and Martins in 1995. It is known from Brazil.
Panegyrtes maculatissimus is a species of beetle in the family Cerambycidae. It was described by Galileo and Martins in 1995. It is known from Brazil.
Panegyrtes clarkei is a species of beetle in the family Cerambycidae. It was described by Galileo and Martins in 2007. It is known from Bolivia.
Panegyrtes bifasciatus is a species of beetle in the family Cerambycidae. It was described by Breuning in 1940. It is known from Brazil.
Panegyrtes sparsepunctatus is a species of beetle in the family Cerambycidae. It was described by Breuning in 1940.
Panegyrtes pseudolactescens is a species of beetle in the family Cerambycidae. It was described by Breuning in 1974. It is known from Brazil.
Panegyrtes apicale is a species of beetle in the family Cerambycidae. It was described by Martins and Galileo in 2005.
Panegyrtes lactescens is a species of beetle in the family Cerambycidae. It was described by Thomson in 1868. It is known from Brazil.
Siphloplecton basale is a species of cleftfooted minnow mayfly in the family Metretopodidae. It is found in all of Canada and the eastern United States.
Il cosmo sul comò is a 2008 sketch comedy film directed by Marcello Cesena and starring Aldo, Giovanni & Giacomo.
References
- ↑ BioLib.cz - Panegyrtes basale. Retrieved on 8 September 2014.