Melanocytes


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Melanocytes

 

in vertebrates and man, pigment cells that synthesize melanins.

There are two kinds of melanocytes: free melanocytes and epithelial melanocytes. Free melanocytes, which are found in the skin, hair follicles, meninges, choroid, and stroma of the iris, originate from the neural crests. When the neural tube closes, they migrate to different parts of the body in the form of mobile, colorless cells, or melanoblasts—the precursors of melanocytes. Epithelial melanocytes, which are found in the pigmented epithelium of the retina, iris, and ciliary folds of the eye, originate from cells of the rudimentary eye.

Melanins are synthesized in the melanocytes in special organelles, or melanosomes, which contain the enzyme tyrosinase. After they fill with melanin, the melanosomes become enzymatically inert pigment granules. The number, shape, and intensity of color of these granules, like the general color of the body, are genetically controlled. Melanocytes are colorless in albinos, in which melanins are not synthesized because of an absence of active tyrosinase.

O. G. STROEVA

References in periodicals archive ?
Histological section of the bladder wall demonstrating pigmented melanocytes (hematoxylin and eosin x100).
Melanocytes produce two forms of melanin, black-brown eumelanin and red-yellow pheomelanin.
Hacker's group conducted clinical trials on 57 Caucasian participants, who were grouped according to their MCIR genotype, and compared the molecular and cellular response of human melanocytes and keratinocvtes in vivo to solar simulated UV radiation.
Previous research had shown that the melanocortin-1 receptor (MC1R) gene plays a key role in protecting melanocytes from UV-induced DNA damage.
6) Our case is unique because cells with obvious sebaceous differentiation were seen in the cyst lining in addition to a proliferation of pigmented, dendritic melanocytes.
The goal of hyperpigmentation treatment includes the degrading of melanosomes, blocking the formation of melanosomes, and slowing the growth of melanocytes.
Like cells in the breast and body, melanocytes house receptor proteins that estrogen can bind to, which then trigger growth within the cell.
Treatment options, depending upon many factors, include corticosteroids, PUVA, Narrow-band UVB phototherapy, topical tacrolimus, laser treatments, skin grafting, transplantation of cultured melanocytes, and de-pigmentation.
By far the most important factor is the concentration and mixture of types of melanin, which are body-own pigments biosynthesized in specialized skin cells called melanocytes.
The most dangerous form of skin cancer is melanoma, which is an overgrowth of the cells known as melanocytes.

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