Venous endothelin guides sympathetic innervation of the developing mouse heart

The innervation of the mouse heart by synaptic nerve terminals during development is critical for proper heart function. Here, Manousiouthakis et al. show that sympathetic axons follow veins to reach and innervate specific areas of the ventricular myocardium and that vascular-derived endothelins have a role as axon guidance cues in this process.