Analysis Tools
mortality/aging
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• homozygotes fail to thrive beyond P8 and generally die by 3 weeks of age
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growth/size/body
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• homozygotes fail to thrive beyond P8
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behavior/neurological
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• homozygotes lack correct coordination of movement and balance
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• homozygotes are unable to right themselves
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hyperactivity
(
J:25565
)
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• homozygotes alternate between periods of hyperactivity and immobility
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nervous system
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• although grossly normal, mutant brains but smaller and contain less neuropile relative to wild-type brains
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• at E13.5-E14, vestibular afferent innervation to the posterior vertical canal is absent, while innervation to the anterior vertical and horizontal canals is severely reduced
• by E14.5-E15, all innervation to the semicircular canals is lost
• in contrast to the semicircular canals, the utricle and saccule show a more modest reduction in nerve fiber density at E13.5-E14
• notably, cochlear innervation remains unnaffected
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• at P7, cochlear afferent fibers are shown to extend to IHCs and OHCs in the basal turn; however, the fiber density to the OHCs is reduced
• also, innervation density to OHCs in the apical and middle turns is more severely reduced than in the basal turn
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• homozygotes show a ~68% reduction in the number of nodose-petrosal sensory neurons
• however, no reductions in the motor neurons of the facial nucleus or lumbar cord are observed
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• the mutant nodose-petrosal complex as a whole is reduced by ~68% in volume, with a similar reduction in the number of neurons in the complex
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• mutant trigeminal ganglia are reduced by ~40% in volume
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• the mutant nodose-petrosal complex as a whole is reduced by ~68% in volume, with a similar reduction in the number of neurons in the complex
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• mutant vestibular ganglia are reduced by >90% in volume
(J:25565)
• in contrast to vestibular ganglia, cochlear ganglia are of normal size
(J:25565)
• at E16.5-E17, homozygotes show a dramatic reduction in vestibular ganglion size relative to wild-type mice
(J:110692)
• a normal-sized vestibular ganglion is observed earler in development (E12.5-E13)
(J:110692)
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• at E16.5-E17, homozygotes show a progressive reduction in vestibular ganglion volume and neuronal number relative to wild-type mice
• by P15, the volume of mutant vestibular ganglia is only 4% of wild-type volume, while the number of vestibular neurons is only 2% of wild-type number
• despite degeneration of vestibular ganglion neurons at P15, sensory hair cells are present in all vestibular regions peripherally (saccule, utricle, cristae ampullaris) and central vestibular nuclei are observed
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hearing/vestibular/ear
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• at P7, cochlear afferent fibers are shown to extend to IHCs and OHCs in the basal turn; however, the fiber density to the OHCs is reduced
• also, innervation density to OHCs in the apical and middle turns is more severely reduced than in the basal turn
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