The developmental basis of the association of congenital deafness with hypothyroidism observed in several human syndromes was earlier investigated by experiments on mice. The offspring of females with chemically induced hypothyroidism were found to have malformations of the organ of Corti, showing that thyroxine played a role in the differentiation of this organ. The present study was undertaken to identify the site of action of the hormone in the developing organ. It appears to be the epithelium of the inner spiral sulcus.

Abnormalities, Drug-Induced↗

PubMedDate not supplied

The inner ear in Bronx waltzer mice.

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Animals↗

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The quivering mutant mouse: hereditary deafness of central origin.

Mice homozygous for the recessive quivering gene are largely unresponsive to sound, although their cochleas appear normal by light microscopy and cochlear hair cells do not degenerate with age. Cochlear potentials and inferior colliculus evoked responses were recorded in quivering mice (qv/qv) and in littermate controls (+/qv or +/+). There were no significant differences between mutants and controls in cochlear microphonic amplitudes or compound action potential thresholds, amplitudes and latencies. However, inferior colliculus evoked responses in mutants were small in amplitude and abnormal in waveform. Latencies were long and thresholds were elevated by at least 50 dB at all frequencies tested. These data suggest that the genetic hearing impairment in quivering mice is retrocochlear.

Action Potentials↗