This image represents a temporal projection (each time point depicted with a different color) of a time-lapse live imaging recording of commissural axons crossing the midline of the developing spinal cord. After these axons have crossed the midline, they turn rostrally towards the brain in a well-organized matter. Nogo receptors play a key role in guiding these axons. For more information, see the article by Vaccaro et al. (pages 4087–4100). Cover image: Alexandre Dumoulin.