The extensions of nerve cells are long, thin fibres, aren’t they? Not so, concludes an international team of cell and neurobiologists 2 December in Nature Neuroscience. At the nanoscale, axons actually look more like a string of pearls (see photo). This went unnoticed for seventy years because specimens for electron microscopy images were not prepared correctly. By using cryogenic freezing, researchers have now succeeded in preserving the bead-like shape. Changes in the size of the ‘beads’ determine how quickly electrical signals travel through the axons. By removing cholesterol, for example, researchers can manipulate that size. (AK)