Sensory transduction in hair cells requires assembly of membrane-bound transduction channels, extracellular tip-links and intracellular adaptation motors with sufficient precision to confer nanometer displacement sensitivity. Here we present evidence based on FM1-43 fluorescence, scanning electron microscopy and RT-PCR that these three essential elements are acquired concurrently between embryonic day 16 and 17, several days after the appearance of hair bundles, and that their acquisition coincides with the onset of mechanotransduction.