Melanocytes are neural crest derived cells that produce melanin, the brown pigment that produces skin color. They do not form desmosomal connections. Melanocytes produce melanin from tyrosine in specialized organelles called melanosomes , which contain tryosinase, an enzyme critical for melanin production. The melanosomes are transferred to keratinocytes via a phagocytic process in which the tips of the melanocyte processes are phagocytosed by keratinocytes. The number of melanocytes differs throughout the body accounting for lighter and darker pigmentation.
All humans have about the same number of melanocytes.
Skin color differences arise from differences in the number, size and arrangement of melanosomes. In dark skin, there are more melanosomes, which are larger and distributed throughout the cytoplasm rather than just in the perinuclear area as in light skin. There are two kinds of melanin, one found in people with dark hair and the other in people with red and blond hair. The epidermis responds to UV light. Melanin darkens via a photochemical reaction.