Editing Wrinkle (section)

=== Causes for aging wrinkles ===
[[File:Nose_%E2%80%93_Caisa.jpg|thumb|upright|A woman of European origin with facial wrinkles]]
Development of facial wrinkles is a kind of [[fibrosis]] of the skin. Misrepair-accumulation aging theory suggests that wrinkles develop from incorrect repairs of injured elastic fibers and collagen fibers.<ref>{{cite arXiv |eprint=0904.0575 |title= Aging as a consequence of Misrepair—a novel theory of aging |last1=Wang |first1=Jicun |last2=Michelitsch |first2=Thomas |last3=Wunderlin |first3=Arne |last4=Mahadeva |first4=Ravi |year=2009 |class= q-bio.TO }}</ref><ref>{{cite arXiv |eprint=1503.07163 |title= Aging as a process of accumulation of Misrepairs |last1=Wang-Michelitsch |first1=Jicun |last2=Michelitsch |first2=Thomas |year=2015 |class= q-bio.TO }}</ref><ref>{{cite arXiv |eprint=1505.01376 |title=Tissue fibrosis: a principal evidence for the central role of Misrepairs in aging |last1=Wang-Michelitsch |first1=Jicun |last2=Michelitsch |first2=Thomas |year=2015 |class=q-bio.TO }}</ref> Repeated extensions and compressions of the skin cause repeated injuries of extracellular fibers in derma. During the repairing process, some of the broken elastic fibers and collagen fibers are not regenerated and restored but replaced by altered fibers. When an elastic fiber is broken in an extended state, it may be replaced by a "long" collagen fiber. Accumulation of "long" collagen fibers makes part of the skin looser and stiffer, and as a consequence, a big fold of skin appears. When a "long" collagen is broken in a compressed state, it may be replaced by a "short" collagen fiber. The "shorter" collagen fibers will restrict the extension of "longer" fibers, and make the “long" fibers in a folding state permanently. A small fold, namely a permanent wrinkle, then appears.