STOCKHOLM, Sweden, Oct. 21 (UPI) -- Swedish scientists say they have discovered skin pigment cells can be formed from completely different cells than previously thought.
The Karolinska Institute scientists say their finding also represents the discovery of a new kind of stem cell.
The body's pigment gives essential protection against UV radiation, the scientists said, noting it consists of a substance called melanin, which is produced by pigment cells in the skin called melanocytes.
According to the established theory of body pigmentation, melanocytes bud off from the spinal cord at an early fetal stage and then migrate to the skin where they remain for the rest of their lives.
In the new study, the findings suggest most melanocytes actually appear later in fetal development from an immature cell type that exists in the skin's nerve fibers. The cells, called Schwann cell precursors, can also be found in adults.
The researchers said their findings can provide new knowledge of how changes in skin pigmentation occur. They describe how a change in cell signaling can make the Schwann precursor cells develop into pigment cells instead, and argue the Schwann cells are really a kind of stem cell.
"This can help science to understand the development of diseases such as melanoma," Professor Patrik Ernfors, who led the study, said. "We've always believed that it develops from melanocytes, but maybe it actually originates in the (Schwann) cells."
The findings appear in the journal Cell.
