Di dalam satu milimiter persegi kulit, terdapat biasanya lebih kurang 1000 ke 2000 melanosit dan meliputi kira-kira 5% ke 10% sel-sel pada lapisan terkematu epidermis. Biasanya, melanosit adalah sebesar 7 mikrometer walaupun saiznya mungkin berlainan.

The difference in skin color between fair people and dark people is due not to the number (quantity) of melanocytes in their skin, but to the melanocytes' level of activity (quantity and relative amounts of eumelanin and pheomelanin). This process is under hormonal control, including the MSH and ACTH peptides that are produced from the precursor proopiomelanocortin.

Albinos lack an enzyme called tyrosinase[meragukan – bincang]. Tyrosinase is required for melanocytes to produce melanin from the amino acid tyrosine.