Cover legend: This cochlear epithelial whole mount from a neonatal mouse shows sensory hair cells (red) and olivocochlear efferent neurons lacking the protein adenomatous polyposis coli (APC, green). Input from olivocochlear efferents is necessary for the normal development of mechanotransduction in sensory hair cells. The loss of APC neonatally in these efferents leads to reduced hearing and abnormal afferent synapse development. For more information, see the article by Hickman et al. (pages 9236–9245).