Quantitative measures reflect degeneration, but not regeneration, in the deafness mouse organ of Corti

The deafness mouse (dn/dn) is a well known model of hereditary deafness uncomplicated by behavioral and motor disturbances. The organ of Corti in this mouse develops a normal complement of sensory and supporting cell structures, yet animals homozygous for this gene never demonstrate any hearing capacity. They are profoundly deaf from birth. Soon after development, the organ of Corti rapidly degenerates, most sensory cells having vanished by 50 days of age. Published observations have suggested that apical regions of the organ of Corti may regenerate some supporting cell structures by 90 days of age. We have quantified changes in organ of Corti structure from 15 to 130 days of age using several different measures. Measures of peak height and total cross-sectional area. as well as a subjective rating scale, all demonstrate consistent degenerative changes during this time period. No evidence for regeneration of supporting or sensory cell structures is noted, although a surprising degree of variability is present in all regions of the organ of Corti which may account for previous claims.