Every tissue in the body supported by its own specialized small stem cell populations. The vast majority of cells in the body, known as somatic cells, are limited in the number of times they can divide. Their telomeres shorten with each cell division, and they become senescent or self-destruct when reaching the Hayflick limit on replication, triggered by short telomeres. Stem cells have no such limitation, and use telomerase to maintain telomere length regardless of the number of divisions they undergo. They divide asymmetrically to generate daughter somatic cells with long telomeres that can replace lost somatic cells in order to maintain tissue function. This split between a small privileged cell population and a large, limited cell population most likely evolved because it greatly reduces the
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https://healthnews010.wordpress.com/2019/05/16/towards-restoration-of-neural-stem-cell-function-in-the-old/
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