Fig. 6. Rescue of cochlear innervation by the B/N allele at P1. Whole mount of transganglionically retrograde labeled ears showing the distribution of afferent fibers to the basal turn in a Nt3-/- mutant (A,D), a wild-type control (B,G) and a B/N mutant mouse at P1 (C,E,F). The B/N mouse shows a dense complement of spiral ganglion neurons and radial fibers throughout the basal turn up to the basal end of the cochlea (Base) similar to the wild-type mouse. In contrast to an almost complete absence of basal turn radial fibers and reduced density of the outer hair cell innervation in the Nt3-/- mice (D), the B/N mutant ear shows dense radial fibers (E) and innervation of both outer hair (OHC) and inner hair cells (IHC). Note that the density of the outer hair cell innervation appears to be even higher in the B/N mice than in wild-type control animals when similar areas of the cochlea are compared (B,C,F,G). Scale bars: 100 µm.
