hearing/vestibular/ear
• inter-stereocilial links are sparse
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• at P4, hair bundles of outer hair cells fail to form a regular V or W shape as in heterozygotes and are malaligned and disoriented
• stereocilia are dispersed and sated to the modiolar side
• some stereocilia are thicker and shorter
• at P8, outer hair cells hair bundles are disarranged and stereocilia are slanted towards the modiolar side to the same extent as at P4
• at 2 months, hair bundles of the outer hair cells were malaligned, and stereocilia on the top of each outer hair cell are not arranged in a row and do not form a staircase
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• hair cells are gradually lost with age beginning at 2 months of age and progressed from the bottom to the apical of the cochlea
• at 2 months 50% of outer hair cells are lost at the basal turn of the cochlea, whereas at the mid and apical turns outer hair cell loss is less than 10% of counted cells
• at 1 year, 50% of outer hair cell is lost from the apical turn and over 90% from the mid turn
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• at 3 weeks, mice have an increased auditory brainstem response (ABR) threshold to 80 dB compared to 20 to 30 dB in wild-type mice
• at 1 year, the ABR threshold at 8 Hz is 93.3 kHz
• however, the latencies of wave peaks was similar to that in wild-type mice
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• no emissions above background are detected
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nervous system
• inter-stereocilial links are sparse
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• at P4, hair bundles of outer hair cells fail to form a regular V or W shape as in heterozygotes and are malaligned and disoriented
• stereocilia are dispersed and sated to the modiolar side
• some stereocilia are thicker and shorter
• at P8, outer hair cells hair bundles are disarranged and stereocilia are slanted towards the modiolar side to the same extent as at P4
• at 2 months, hair bundles of the outer hair cells were malaligned, and stereocilia on the top of each outer hair cell are not arranged in a row and do not form a staircase
|
• hair cells are gradually lost with age beginning at 2 months of age and progressed from the bottom to the apical of the cochlea
• at 2 months 50% of outer hair cells are lost at the basal turn of the cochlea, whereas at the mid and apical turns outer hair cell loss is less than 10% of counted cells
• at 1 year, 50% of outer hair cell is lost from the apical turn and over 90% from the mid turn
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• at 12 months, spiral ganglion neurons and nerve bundles under the sensory epithelium of the cochlea are missing at the basal turn of the cochlea
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