Melanocytes  are melanin-producing cells located in the bottom layer (the stratum basale) of the skin’s epidermis, the middle layer of the eye (the uvea), the inner ear, meninges, bones, and heart. Melanin is a pigment that is responsible primarily for the color of skin. (wikipedia)
mouseover for arrows                                    Virtual microscopy
They can be identified by the presence of a nucleus surrounded by a clear space.  The cells with brownish pigments are actually keratinocytes that have received melanin granules from the melanocytes by pigment donation.  (from Michigan Histology)
Melanocytes comprise from 5% to 10% of the cells in the basal layer of epidermis.

Melanocytes make the melanin, but they don’t keep it for long. Instead, they pass it to the neighboring keratinocytes which then carry it up through the layers and out of the system. Although you can’t see them under light microscopy, melanocytes have long and extensive processes called dendrites, that reach out and contact many keratinocytes, to facilitate pigment transfer. In places where melanocytes are concentrated and/or very active, localized deep pigmentation occurs.

The melanocytes, unlike the keratinocytes, are a very stable population of cells. They normally do not divide, and their life span is measured in years to decades, rather than the few days of the keratinocytes.  (adapted from wikipedia)

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