Library · Physiology
Skin color
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Skin color is not spread out evenly: it is stored in little packets. They are called melanosomes, and they carry melanin, the pigment, inside. Melanocytes, cells in the basal layer of the epidermis, that is, the bottom floor of the outermost layer of the skin, hand them off to keratinocytes, the cells that make up the bulk of that layer, and there they build up.
The tone you see depends on two things at once. One is the pigment mix: eumelanin, which is brown or black, and pheomelanin, which is yellow or red. The other is how many melanosomes there are and how they are distributed.
That is where the detail almost nobody knows comes in. In light skin, melanocytes generally hold clusters of two or three melanosomes together, and in dark skin there tend to be more melanosomes, spread out one by one.
Think of salt scattered on a table: in some spots it falls in little heaps of two or three grains, and in others it lies loose and more plentiful.
In brief
Skin color comes from melanin-containing melanosomes that melanocytes in the basal layer of the epidermis transfer to keratinocytes, where they build up.
It depends on the ratio of eumelanin, brown or black, to pheomelanin, yellow or red, and on the number and distribution of those melanosomes.
In light skin, melanocytes generally hold clusters of two or three melanosomes; in dark skin there tend to be more, spread out one by one.
Scattered salt: little heaps here, loose and more plentiful there.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingBiochemistry, Melanin, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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