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Skin ageing results from both the passage of time and from extrinsic forces, predominantly solar ultraviolet irradiation. Intrinsic ageing is characterized by fine wrinkling and homogenous colour on sun‐protected sites whereas extrinsic ageing is characterized by fine and coarse wrinkling, erythema and dyspigmentation on sun‐exposed sites. Two distinct phenotypes of extrinsic ageing have emerged: atrophic and hypertrophic variants. Tools to measure and quantify skin ageing have been developed and offer therapeutic and research applications. Molecular mechanisms distinguishing intrinsic and extrinsic skin ageing are discussed. The implications of skin ageing are cosmetic, medical and social in nature.
Keywords skin, ageing, photoageing, extrinsic ageing, natural ageing, intrinsic ageing, collagen, wrinkles, mechanical tension, collagen fragmentation