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As normal cells approach the end of their ability to divide, they incur
hundreds of biological changes that affect virtually all of their activities.
Many of these changes are similar, if not identical, to the kinds of changes
that we see occurring in aging humans themselves. Thus, the study of cellular
senescence continues to provide important clues to the aging process at
the most fundamental level--the cell.
Some of the senescent cells' functional losses appear to contribute to
the aging process. For example, certain skin cells produce collagen during
their younger, reproductive years. When they reach senescence and can
no longer divide, they produce collagenase, an enzyme that breaks down
collagen. Some researchers suggest that this process may be responsible
for the thinning and wrinkling of skin as we age.
Some scientists also speculate that the growth arrest associated with
replicative or reproductive senescence may retard the regeneration or
repair of damaged tissue, which could play a role in the aging of the
body.
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