melanin

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melanin Any of a group of polymers, derived from the amino acid tyrosine, that cause pigmentation of eyes, skin, and hair in vertebrates. Melanins are produced by specialized epidermal cells called melanophores (or melanocytes); their dispersion in these cells is controlled by melanocyte-stimulating hormone and melatonin. Certain invertebrates, fungi, and microorganisms also produce melanin pigments. The `ink' of the octopus and squid is a notable example. Hereditary albinism is caused by the absence of the enzyme tyrosinase, which is necessary for melanin production.

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