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a limitation in the number of times that cells can divide; appears to be a basic feature of somatic cells except for most tumor cells and possibly some stem cells. The cell division s counting mechanism is posited to exist as a consequence of a telomere-shortening hypothesis.
senescence(se-nes'ens) [L. senescens, growing old]
1. The process of growing old.
2. The period of old age.
Aging (typically of cells, but also of whole organisms) that occurs much earlier than is expected under healthy or optimal conditions.