The skin's pigment cells can be formed from completely different cells than has hitherto been thought, a new study from the Swedish medical university Karolinska Institutet shows. The results, which are published in the journal Cell, also mean the discovery of a new kind of stem cell.The body's pigment gives essential protection against UV radiation. It is made up of a substance called melanin, which is produced by pigment cells in the skin called melanocytes. According to the established theory of body pigmentation, these melanocytes bud off from the spinal cord at an early foetal stage and then migrate to the skin where they remain for the rest of their lives. Scientists at Karolinska Institutet in Stockholm have now shown that most melanocytes actually appear later on in foetal development from an immature cell type that exists in the skin's nerve fibres. These cells, called Schwann cell precursors (SCPs), can also be found in adults. In addition to this, the scientists have demonstrated how neuronal damage in adults can excite the maturation of melanocytes to form hyperpigmentation around the affected nerves.
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