title: Stereociliary anomaly in the guinea pig: effects of hair bundle rotation on cochlear sensitivity.
abstract: Histological analysis of cochleas from 100 albino guinea pigs (Hartley strain) obtained from Charles River Laboratories revealed an apparently congenital anomaly in 24% of animals, with roughly equal prevalence in males and females. In affected animals, 15-50% of the first-row outer hair cells (OHCs) showed distinctly abnormal orientation of the W-shaped stereociliary array. These abnormal hair bundles could be rotated by up to 180 degrees from the normal quasi-radial orientation. Second- and third-row OHCs appeared normal in all cases. Cochlear sensitivity was assayed in a subset of animals via compound action potentials (CAPs): CAP thresholds in affected animals were, on average, elevated by 5-10 dB with respect to normal controls. If the contributions of individual OHCs to cochlear 'amplification' add linearly, and if the total OHC contribution corresponds to approximately 45 dB of 'gain', a quantitative correlation of the degree of stereociliary rotation and the degree of threshold shift in these ears suggests that first-row OHCs make a larger contribution to the cochlear amplifier than either of the other OHC rows.
authors.affiliation: Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.
authors.forename: N
authors.initials: N
authors.lastname: Yoshida
authors.forename: M C
authors.initials: MC
authors.lastname: Liberman
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002923:Cilia / Q000648:ultrastructure*; D003051:Cochlea / Q000503:physiopathology*; D004056:Differential Threshold / Q000502:physiology; D006168:Guinea Pigs / Q000002:abnormalities*; D018072:Hair Cells, Auditory, Outer / Q000002:abnormalities* / Q000648:ultrastructure*; D012016:Reference Values; D012399:Rotation