Analysis Tools
hearing/vestibular/ear
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• at 8 weeks, homozygotes show variable and scattered OHC loss in the basal-most region of the cochlea
• OHC loss is restricted to cochlear frequency regions well above that where the threshold shift is observed
• however, no loss of IHCs or cochlear neurons is observed, and all other structures of the cochlear duct, including the stria vascularis, appear unaffected
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• at 8 weeks, homozygotes show a consistent and significant loss of type IV fibrocytes in the spiral ligament throughout most of the basal turn
• all cell nuclei are absent in this region of the spiral ligament, and only the fibrous network is observed
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• at 6 to 8 weeks, homozygotes show a significant reduction of 20 to 25 mV in the endolymphatic potential, as measured in the basal turn at roughly the 45-kHz place
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• at 6 to 8 weeks, suprathreshold ABR amplitudes are significantly reduced at frequencies of >16 kHz
• however, no significant changes in response waveforms are observed
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• at 6 to 8 weeks, homozygotes display ABR threshold elevatations by 20-45 dB for frequencies of >16 kHz
• however, at lower frequencies (<16 kHz), ABR threshold elevations are non-significant (<10 dB)
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• at 6 to 8 weeks, homozygotes display significant DPOAE threshold elevatations for frequencies of >16 kHz
• in addition, suprathreshold DPOAE amplitudes are significantly reduced at frequencies of >16 kHz
• however, at lower frequencies (<16 kHz), DPOAE threshold elevations are non-significant, and no significant changes in response waveforms are observed
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• at 6 to 8 weeks, some mutant ears show no DPOAEs at the highest test sound levels (80 dB SPL)
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• at 12 hrs after a 2-hr exposure to an octave noise band (8 to 16 kHz) at 89 dB SPL, 6-8-wk-old homozygotes display significantly higher temporary threshold shifts in both ABR and DPOAE than wild-type mice
• however, the efferent innervation of hair cells and the classic efferent inhibition of OHCs remain unaffected
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• at 6 to 8 weeks, homozygots display significant high-frequency hearing loss
• however, hippocampal and vestibular sensory-end organ morphology and function remain normal at 2 months of age
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growth/size/body
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• at 4 months of age, the weights of male and female homozygotes are ~89% and ~87% of those of wild-type males and females, respectively
• however, no significant weight differences in either sex are observed at 2 months or earlier
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nervous system
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• at 8 weeks, homozygotes show variable and scattered OHC loss in the basal-most region of the cochlea
• OHC loss is restricted to cochlear frequency regions well above that where the threshold shift is observed
• however, no loss of IHCs or cochlear neurons is observed, and all other structures of the cochlear duct, including the stria vascularis, appear unaffected
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behavior/neurological
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• at 2 months, homozygotes behave normally in the rotarod, Morris water maze, and swim test relative to wild-type
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skeleton
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• at 8 weeks, homozygotes show a consistent and significant loss of type IV fibrocytes in the spiral ligament throughout most of the basal turn
• all cell nuclei are absent in this region of the spiral ligament, and only the fibrous network is observed
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