中文摘要：

单纯由时间所致的人皮肤程序性或内源性老化及改变，与由环境损伤所致的多重性损伤或外源性老化加速之间有着明显的不同，后者的进程主要由日光中的紫外线所介导，故称为光老化。端粒及端粒酶在细胞的生命周期中起着不容忽视的作用，与细胞的老化密切相关。皮肤内源性老化主要由细胞周期中进行性的端粒缩短所致，而在光暴露的皮肤，内源性老化的进程被环境因素所放大。

英文摘要：

Human skin provides an instructive contrast between programmed or intrinsic aging, whic h is attributable to the passage of time alone, and superimposed additional changes or extrinsic aging that results from environmental damage. The latter process is mainly due to ultraviolet irradiation and is termed as photoaging. Telomere and telomerase exert essential roles in cell cycle, and closely associated with cell aging. The intrinsic aging primarily results from the progressive shortening of telomere, while the process is enlarged in sun-exposed skin by the environment.