Haircellbearing

Haircellbearing describes tissues or cell populations that bear hair cells, specialized mechanosensory cells with apical hair bundles consisting of stereocilia and, in some species, a kinocilium. In vertebrates, haircellbearing epithelia are found in the auditory and vestibular organs of the inner ear, including the organ of Corti in the cochlea, the maculae of the utricle and saccule, and the cristae of the semicircular canals. Similar sensory epithelia exist in the lateral line system of fishes and amphibians.

Each hair cell has a bundle of stereocilia that deflects in response to mechanical stimuli. Deflection toward the tallest stereocilium increases the probability that mechanotransduction channels open, allowing cation influx and generating a receptor potential that triggers neurotransmitter release to afferent neurons. Tip links connect adjacent stereocilia, enabling mechanical gating; adaptation mechanisms reset sensitivity.

In mammals, hair cells are supported by surrounding supporting cells. Inner hair cells primarily convey acoustic information to the brain, while outer hair cells amplify and tune responses. Haircellbearing epithelia are vulnerable to damage from excessive noise, ototoxic drugs, or aging, often resulting in permanent hearing or balance deficits. Some non-mammalian vertebrates can regenerate hair cells, a capacity that informs regenerative research, including gene therapy and stem-cell approaches.