Analysis Tools
growth/size/body
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• homozygotes are larger than wild-type littermates as a result of multiorgan hyperplasia
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hearing/vestibular/ear
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• at P6, homozygotes exhibit hyperplasia of the organ of Corti
• continued presence of proliferating cells in the postnatal organ of Corti, as well as abnormal persistence of Cdkn1b expression in mature supporting cells indicate a role for Cdkn1b in maintaining these cells in a quiescent state
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• homozygotes develop supernumerary hair cells in both the inner and outer rows of hair cells
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• at P6, the mutant inner row contains a partly disorganized line of at most two hair cells, whereas wild-type mice normally contain a single row of inner hair cells
• in homozygotes, IHC numbers are increased by a mean of 23% relative to wild-type mice
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• at P6, homozygotes contain four, partly disorganized, rows of cochlear outer hair cells (OHCs) instead of the expected three rows of OHCs seen in wild-type mice
• in homozygotes, OHC numbers are increased by a mean of 36% relative to wild-type mice
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• homozygotes develop an excess number of supporting cells, including pillar cells, separating IHCs from OHCs and occupying the area of the tunnel
of Corti
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• at P6, homozygotes display supernumerary cells in the pillar cell region of
the organ of Corti, where normally one inner pillar and one outer pillar cells are present in wild-type mice
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• at 10 weeks of age, homozygotes display a significantly elevated mean, click-evoked, ABR threshold (77 db SPL) relative to age-matched wild-type mice (20 db SPL)
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• at 10 weeks of age, homozygotes are severely hearing-impaired
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nervous system
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• homozygotes develop supernumerary hair cells in both the inner and outer rows of hair cells
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• at P6, the mutant inner row contains a partly disorganized line of at most two hair cells, whereas wild-type mice normally contain a single row of inner hair cells
• in homozygotes, IHC numbers are increased by a mean of 23% relative to wild-type mice
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• at P6, homozygotes contain four, partly disorganized, rows of cochlear outer hair cells (OHCs) instead of the expected three rows of OHCs seen in wild-type mice
• in homozygotes, OHC numbers are increased by a mean of 36% relative to wild-type mice
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cellular
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• at E16, anti-PCNA staining of the organ of Corti indicates that proliferation of sensory cell progenitors abnormally continues after E14 (i.e. past the normal time of cell cycle withdrawal), leading to the appearance of supernumerary hair cells and supporting cells in mutant mice
• at E16, PCNA-positive cells are observed in the Deiters' cell region
beneath the newly differentiated hair cells stained with anti-myosin VIIa
• at P6, PCNA-positive cells are no longer seen in Deiters' cell region as they are at E16, but appear in clusters in the region of Hensen's cells, lateral to the outermost row of OHCs, as well as in the pillar cell regions separating IHCs and OHCs
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behavior/neurological
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• no obvious behavioral defects related to vestibular function, such as circling or balance deficits, are observed
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