Ultraviolet light induces melanin production from melanocyte cells to cause sun tanning of skin. Oral melanoacanthoma are benign pigmented lesions due to dendritic melanocyte proliferation and superficial epithelium acanthosis. One melanocyte supplies melanin to thirty-six keratinocytes according to signals from the keratinocytes. The intermediate lobe of pituitary gland secretes only one enzyme that is melanocyte stimulating hormone. There are in addition populations of cells producing somatostatin, angiotensin II and melanocyte stimulating hormone. UV light stimulates melanocyte activity, and where concentration of the cells is greater, hyperpigmentation occurs. The death of the melanocyte stem cells causes the onset of graying. Because melanocyte cells continually produce pigment, in theory eye color can be changed. Piebaldism is a rare autosomal dominant disorder of melanocyte development. This is important when considering mast cell and melanocyte development. The precursor of the melanocyte is the melanoblast. Only one such cell type, the melanocyte, has been identified in these animals.