Human Differences
Typically, between 1000 and 2000 melanocytes per square millimeter of skin are found. Melanocytes comprise from 5% to 10% of the cells in the basal layer of epidermis. Although their size can vary, melanocytes are typically 7 μm in length.
The difference in skin color between lightly and darkly pigmented individuals 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. Tyrosinase is required for melanocytes to produce melanin from the amino acid tyrosine.
Read more about this topic: Melanocyte
Famous quotes containing the words human and/or differences:
“I am secretly afraid of animals.... I think it is because of the usness in their eyes, with the underlying not-usness which belies it, and is so tragic a reminder of the lost age when we human beings branched off and left them: left them to eternal inarticulateness and slavery. Why? their eyes seem to ask us.”
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