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Progress has been made in defining the structural and functional alterations that occur in skin with age. Changes caused solely by longevity have been delineated from changes due to long-term sun exposure. Uneven pigmentation is 1 of the major changes in the gross morphologic characteristics of the aging skin and is much more marked in sun-exposed areas. In the epidermis, melanin pigments are good indicators of photoaging. Ultraviolet radiation plays a major role in the induction of melanocyte aging and may severely damage the melanocyte system of the skin, resulting in both hypermelanotic and hypomelanotic lesions.
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Jérôme Castanet (1997) studied this question.
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