melanin


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melanin

 [mel´ah-nin]
any of several closely related dark, sulfur-containing pigments normally found in the hair, skin, ciliary body, choroid of the eye, pigment layer of the retina, and certain nerve cells. They occur abnormally in the tumors known as melanomas and may be excreted in the urine when such tumors are present (melanuria).

mel·a·nin

(mel'ă-nin),
Any of the dark brown to black polymers of indole-5,6-quinone and/or 5,6-dihydroxyindole 2-carboxylic acid that normally occur in the skin, hair, pigmented coat of the retina, and inconstantly in the medulla and zona reticularis of the adrenal gland. Melanin may be formed in vitro or biologically by oxidation of l-tyrosine or l-tryptophan, the usual mechanism being the enzymatic oxidation of l-tyrosine to 3,4-dihydroxy-l-phenylalanine (dopa) and dopaquinone by monophenol monooxygenase, and the further oxidation (probably spontaneous) of this intermediate to melanin. Compare: eumelanin, pheomelanin.
Synonym(s): melanotic pigment
[G. melas (melan-), black]

melanin

/mel·a·nin/ (mel´ah-nin) any of several closely related dark pigments of the skin, hair, choroid coat of the eye, substantia nigra, and various tumors, produced by polymerization of oxidation products of tyrosine and dihydroxyphenol compounds.

melanin

(mĕl′ə-nĭn)
n.
Any of a group of naturally occurring dark pigments, especially the pigment found in skin, hair, fur, and feathers.

melanin

[mel′ənin]
Etymology: Gk, melas, black
a black or dark brown pigment that occurs naturally in the hair, skin, and iris and choroid of the eye. See also melanocyte.

melanin

A dark natural pigment found in the epidermis or skin adnexal structures. It is a complex polymer of oxidised tyrosine synthesised from DOPA and dopaquinone in response to actinic stimulation and bound to a carrier protein by melanocytes—in the skin, mucous membrane, pia arachnoid, retina, inner ear and mesentery. Melanin is detected in tissue sections by the Fontana-Masson stain.

melanin

 Physiology A dark natural body pigment found in the epidermis or skin adnexal structures. See Albinism, DOPA, Melanoma.

mel·a·nin

(mel'ă-nin)
Any of the dark brown to black pigments that occur in the skin, hair, pigmented coat of the retina, and medulla and zona reticularis of the suprarenal gland.
[G. melas (melan-), black]

melanin

The body's natural colouring (pigment) found in the skin, hair, eyes, inner ears and other parts. In body cells, melanin is bound to protein. It is a complex POLYMER formed from the amino acid TYROSINE (4-hydroxphenylalanine) by oxidation via dopa and dopaquinone.

melanin

a dark brown or black pigment found in skin or hair and in the iris and choroid layer of the EYE. Melanin is found in special cells called MELANOPHORES. See ALBINISM, DOPA.

Melanin

A dark insoluble pigment found in humans in the skin, hair, choroid layer of the eye, and a part of the brain called the substantia nigra.

melanin

dark brown/black pigment within melanosomes of epidermal melanocytes (see melanosome)

melanin (meˑ·l·nin),

n a substance produced by melanocytes found in the deepest layer of the epidermis; protects the skin from the effects of the sun's harmful rays. Variations in skin color are a result of the level of melanin produced by each individual.

melanin

Dark brown to black pigment normally present in the skin, the hair, the choroid, the iris, the retina, the ciliary body, the cardiac tissue, the pia mater and the substantia nigra of the brain. It is absent in albinos. See albinism; fuscin; melanocyte; melanosis; choroidal naevus; retinal pigment epithelium.

mel·a·nin

(mel'ă-nin)
Any of the dark brown to black pigments that occur in the skin, hair, pigmented coat of the retina, and medulla and zona reticularis of the suprarenal gland.
[G. melas (melan-), black]

melanin (mel´ənin),

n the dark amorphous pigment of melanotic tumors, skin, oral mucosa, hair, choroid coat of the eye, and substantia nigra of the brain.

melanin

a dark, sulfur-containing pigment normally found in the hair, skin, ciliary body, choroid of the eye, pigment layer of the retina, and certain nerve cells. It occurs abnormally in certain tumors, known as melanomas, and is sometimes excreted in the urine when such tumors are present (melanuria).

melanin deficiency
hypopigmentation, leukoderma, hypomelanosis.
excess melanin
hyperpigmentation, hypermelanosis, melanism, melanoderma, melanotrichia.
melanin-stimulating hormone
see melanocyte-stimulating hormone.
References in periodicals archive ?
While increased melanin production can be a nuisance to those who experience it, age spots can be treated.
A'The sun triggers the production of melanin, meaning that, unless you are extremely regimented in applying SPF daily, you will probably suffer some after-effects of hot weather - in the form of extra freckles and dark spots (aka pigmentation),' says Victoria.
Julien Farel Magnifique Fortifying Serum contains a hexapeptide said to increase melanin and stimulate pigmentation.
basically its the opposite of an albino when the individual produces more melanin than normal.
While is seems logical that the loss of the pigment melanin would serve as a compensatory mechanism, allowing for more irradiation of the skin surface and therefore more vitamin D production, this hypothesis is flawed for many reasons, he continued.
The synthesis of melanin begins with the hydroxylation of L-tyrosine to L-dihydroxyphenyl-alanine (L-DOPA), and then the oxidation of DOPA to DOPAquinone.
The increased black melanin production could have given other benefits that helped individuals to pass on their genes to the next generation - such as preventing damage to sweat glands or the destruction of folate.
Melanin is derived from the Greek word melas, meaning "black," and it is a pigment found in most organisms.
For both color morphs, melanin usually masks the mandible color within a few weeks of fledging (Grant and Grant 1989).
Results: Three months after the treatment, the mean gingival melanin pigmentation score decreased from 41.
Epidermal melasma is characterized by the presence of excess melanin in the superficial layers of the skin.
Homogeneity of hemoglobin and melanin maps was positively correlated with that of unprocessed images (r = 0.