eLife assessment
This important study provides new insights into the maturation of ribbon synapses in zebrafish neuromast hair cells. Convincing evidence, based on live-cell imaging and pharmacological and genetic manipulations, is provided to show that the formation of this synaptic organelle is a dynamic process involving the fusion of presynaptic elements and microtubule transport. These findings will be of interest to neuroscientists studying synapse formation and function and should inspire further research into the molecular basis for synaptic ribbon maturation.