These delicate red lines are nerve cells – the body’s electrical signalling wires – stretched out under a fluorescence microscope. Red highlights a fatty molecule called myelin, which acts a bit like plastic electrical tape, insulating the thin fibre of the nerve encased within it. To speed up transmission, electrical impulses can jump between gaps (seen here as faint vertical stripes) in this myelin casing. At the top is a healthy mouse nerve, while the two below are taken from mice carrying genetic faults in a gene called PMP2. The gaps in the myelin are much closer together, meaning that signals don’t travel as efficiently along the nerve. This particular genetic fault mimics the mistake found in one human family with the inherited syndrome known as Charcot-Marie-Tooth disease, which causes muscle weakness and loss of movement and sensation, helping to shed light on the underlying causes of their health problems.
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