Analysis Tools
hearing/vestibular/ear
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• at 12 weeks of age extensive fusion is seen
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• fusion of stereocilia is apparent in the basal cochlear region as early as two weeks of age
• at 8 weeks of age stereocilia on the remaining outer hair cells in the basal region are fused
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• gradual loss of inner and outer hair cells is seen starting in the basal turn of the cochlea and spreading towards the apical region leading to a collapse of the organ of Corti
• at 4 weeks of age signs of degeneration are seen in all turns of the cochlea, most prominently in the basal turn
• hair cell degeneration is more prominent at 8 weeks of age
• at all time points examined degeneration of outer hair cells is more advance and severe than that of inner hair cells
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• at 12 weeks of age extensive loss of inner hair cells is seen
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• degeneration of outer hair cells is apparent in the basal cochlear region as early as two weeks of age
• by 8 weeks of age most outer hair cell bundles are missing in the basal cochlear turn and some are missing in the mid cochlear turn
• by 12 weeks of age the basal region lacks outer hair cell bundles
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• loss of hair cells leads to the eventual collapse of the organ of Corti
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• by 8 weeks of age
• Background Sensitivity: increase in ABR threshold is more severe in mice on a C57BL/6 background compared to mice outcrossed to CBA/H
• Background Sensitivity: however, severity is similar in C57BL/6 and mixed C57BL/6 and BALB/c backgrounds
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• progressive hearing loss beginning by 8 weeks of age with mice severely deaf by 12 weeks of age
• Background Sensitivity: loss of hearing is more severe in mice on a C57BL/6 background compared to mice outcrossed to CBA/H, authors indicate this is due to the presence of the Cdh23ahl allele in the C57BL/6 strain
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behavior/neurological
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• circling and head tossing behaviors are not seen
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nervous system
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• peripheral nerve conductance is not significantly different from heterozygous controls
• no degeneration of the cochlear nerve fibers is detected
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• at 12 weeks of age extensive fusion is seen
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• fusion of stereocilia is apparent in the basal cochlear region as early as two weeks of age
• at 8 weeks of age stereocilia on the remaining outer hair cells in the basal region are fused
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• gradual loss of inner and outer hair cells is seen starting in the basal turn of the cochlea and spreading towards the apical region leading to a collapse of the organ of Corti
• at 4 weeks of age signs of degeneration are seen in all turns of the cochlea, most prominently in the basal turn
• hair cell degeneration is more prominent at 8 weeks of age
• at all time points examined degeneration of outer hair cells is more advance and severe than that of inner hair cells
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• at 12 weeks of age extensive loss of inner hair cells is seen
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• degeneration of outer hair cells is apparent in the basal cochlear region as early as two weeks of age
• by 8 weeks of age most outer hair cell bundles are missing in the basal cochlear turn and some are missing in the mid cochlear turn
• by 12 weeks of age the basal region lacks outer hair cell bundles
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• reduction in the number of spiral ganglia cells and increased vacuolation in the remaining cells at the same time as loss of cochlear hair cells
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