melanin

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melanin a brown pigment in the skin and elsewhere. It is made in melanocytes, which are cells in the deepest layer of the epidermis, and these distribute granules of pigment to the other skin cells. Synthesis is stimulated by sunlight, and also by a hormone from the anterior pituitary gland. This is the pigment in simple moles and freckles, and in the areolar of the nipples; melanocytes are the cells which become cancerous in a malignant melanoma. Other sites are in hair, behind the retina of the eye, and in part of the adrenal gland.

S. J.


See pigmentation; skin.

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