The cells in our bodies are constantly dividing and replenishing themselves, but neurons—the brain cells that transmit messages via electric and chemical signals—are a special case. Researchers used to believe that people could not replenish neurons or grow new ones after they reached maturity. Now, scientists know that new neurons can indeed form, but only from specialized stem cells, the New Scientist says.
Crawfish, however, are different. Scientists just discovered that they chug out new neurons like crazy, by converting lowly blood cells into specialized cells, which they use to fix damaged eye stalks and smell circuits, the New Scientist reports:
They utilise what amounts to a "nursery" for baby neurons, a little clump at the base of the brain called the niche.
In crayfish, blood cells are attracted to the niche. On any given day, there are a hundred or so cells in this area. Each cell will split into two daughter cells, precursors to full neurons, both of which migrate out of the niche. Those that are destined to be part of the olfactory system head to two clumps of nerves in the brain called clusters 9 and 10. It's there that the final stage of producing new smell neurons is completed.
Some mysteries remain, such as how the blood cells themselves are specifically reprogrammed to become completely different cells. The ultimate hope is that crawfish can teach us something about our own ability to reprogram cells, perhaps leading to breakthroughs that could help patients with neurodegenerative diseases such as Parkinson's, the New Scientist writes.