stereocilierna

Stereocilierna are the organized arrays of stereocilia on sensory hair cells that form the core of mechanosensation in the vertebrate inner ear. They are slender, actin-based projections that extend from the apical surface of hair cells and are arranged in a hair bundle with a staircase-like height pattern. The bundle converts mechanical stimuli from fluid movement into electrical signals.

Each stereocilierna contains a core of cross-linked actin filaments, anchored at the cuticular plate and capped at the tip. In many species, adjacent stereocilia are connected by extracellular tip links and lateral links, enabling coordinated deflection of the bundle. Deflection toward the tallest row increases tension on tip links, opening mechanotransduction channels in the stereociliary membrane and allowing cation influx that depolarizes the hair cell. Deflection in the opposite direction relaxes the links and closes the channels.

Stereocilierna development proceeds during embryogenesis as actin polymerizes to lengthen the stereocilia and stabilizes their arrangement. Tip-link proteins such as cadherin 23 and protocadherin 15, along with actin-binding proteins, maintain bundle integrity and mechanosensitivity. Growth and maintenance involve motor and scaffolding proteins that regulate tension and renewal of the actin core.

Damage to stereocilierna from loud sound, ototoxic drugs, or disease can impair mechanotransduction and cause hearing or balance deficits. Regeneration of stereocilia is limited in mammals but occurs in some other vertebrates, and is a focus of regenerative medicine research.

Etymology: Stereocilierna combines elements related to the stereocilia of hair cells and the diminutive -na form in some languages.