Specialized cells, the scientists report, point the way for neurons stretching from newly grown eyes to the brain of the worm, helping them connect correctly.
Gathering these and other insights from the study of flatworms may someday help scientists interested in helping humans regenerate injured neurons.
When the researchers transplanted an eye from one animal to another, the neurons growing from the new eye always grew toward these cells.
Removing those cells meant the neurons got lost and did not reach the brain.
But by the time most animals grow into adults, these cells are usually long-gone.
In flatworms, however, cells that perform this guiding role apparently exist in adults.
Getting the right cells to grow to replace those lost is only part of the process, though.
Reddien and his colleagues are planning to continue looking for cells that give regenerating neurons a guide to follow