n. a dark-brown to black pigment occurring in the hair, the skin, and in the iris and choroid layer of the eyes. Melanin is contained within special cells (chromatophores or melanophores) and is produced by the metabolism of the amino acid tyrosine. Production of melanin by melanocytes in the epidermis of the skin is increased by the action of sunlight (producing tanning), which protects the underlying skin layers from the sun’s radiation.... melanin
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