The stereocilium is a finger-like projection forming the hair bundle on the apical surface of sensory hair cells in the cochlea. Stereocilia stiffness and function depend on the several hundreds of uniformly polarized and tightly cross-linked actin filaments. Stereocilia cytoskeleton shows continuous turnover with actin filament assembly occuring at the stereocilium tip and its disassembly at the base so that stereocilium length is maintained in a dynamic steady-state. This staircase-like bundle of stereocilia is responsible for mechanosensation and ultimately the perception of sound.

› Cellular component

› stereocilium [ GO:0032420 ]