melaniinista

Melanin is a pigment produced by specialized pigment-producing cells called melanocytes. These cells reside mainly in the epidermis, the outermost layer of the skin, but are also found in hair follicles, the iris of the eye, and certain parts of the inner ear and brain. Melanin production occurs within organelles called melanosomes inside melanocytes. The biosynthesis starts with the amino acid tyrosine and involves the enzyme tyrosinase; the process yields two main types of melanin: eumelanin (brown to black) and pheomelanin (red to yellow). The relative amounts of these pigments determine a person’s color of skin, hair, and eyes.

Melanosomes are transferred from melanocytes to surrounding keratinocytes, where they form protective caps over cell nuclei and absorb ultraviolet radiation, contributing to photoprotection. The amount and distribution of melanin are influenced by genetics (notably variants in MC1R and related pathways), hormones, age, and UV exposure. Increased UV exposure stimulates melanogenesis and tanning, while protective behaviors and sunscreen can modulate this response.

Clinical variation includes naturally higher melanin content in some populations, resulting in darker skin tones, and conditions of hypopigmentation (albinism, vitiligo) or hyperpigmentation (melasma, postinflammatory hyperpigmentation). Melanin also has roles beyond skin color, including antioxidant properties and, in some tissues, contributions to optical and neural functions. Ongoing research investigates the full extent of its protective roles and the genetic regulation of melanin synthesis.