Melanocyte
A melanocyte is a cell in the lower epidermis that produces melanin, the pigment giving skin, hair and eyes their colour. Each melanocyte supplies pigment to a group of neighbouring cells, which carry it towards the surface.
Melanocytes sit spaced along the base of the epidermis, and each one serves a surrounding group of keratinocytes rather than working alone. Pigment is manufactured inside the melanocyte, packaged, and handed across to those neighbours, which carry it upward as they mature.
What melanin does there is absorb ultraviolet radiation. It positions itself over the cell nucleus, which has been described as holding a parasol above the genetic material, and that is the whole purpose of skin pigmentation as a biological arrangement.
Differences in skin tone come less from the number of melanocytes, which varies surprisingly little, than from how much pigment they produce and which forms of it. Production also responds to exposure, which is what tanning is.
The word recurs across conditions that look unrelated. Vitiligo involves melanocytes ceasing to function in patches. Melasma involves them working harder in particular areas. Moles are clusters of them. Melanoma is a cancer arising from them.
That single cell type therefore connects a large part of the pigmented side of dermatology, which is why clinicians reach for the word so often.
Last updated .