Sometimes it is the extremes that point the way forward. Researchers at the University of Pennsylvania School of Medicine have induced nerve fibers – or axons – to grow at rates and lengths far exceeding what has been previously observed. To mimic extreme examples in nature and learn more about neuronal physiology, they have mechanically stretched axons at rates of eight millimeters per day, reaching lengths of up to ten centimeters without breaking. This new work has implications for spinal cord and nerve-damage therapy, since longer implantable axons are necessary for this type of repair.