ErbB2 mutants with Sox10 conditional mutants have similar unusual spiral ganglion position but differ in fiber projections and apoptotic neuron ratio.

<p>Injection of lipophilic dyes into cochlear nuclei label spiral ganglion cells in the center of cochlea (A, B) and elongated radial fibers (RF). Only Sox10 mutants show a massive projection of spiral ganglion afferents to the lateral wall (insert in B). ErbB2 mutants have a severe reduction in radial fibers with very few extending into the organ of Corti (shown by PLP-eGFP) and the lateral wall (LW). In contrast, Sox10 mutants have a denser organ of Corti innervation (shown with Myo7a immunoreactivity in D) and many fibers to the lateral wall. One in 5 spiral ganglion neurons of ErbB2 mutants is apoptotic (E) and rare apoptotic profiles are also found in Sox10 mutants (F). Markers for apoptosis such as anti-activated caspase3 immunocytochemistry (G’) and PSVue (G”) confirm the occasional dying cell (G, G’”) in Sox10 conditional mutant mice. Abbreviations: LW, lateral wall; OC, organ of Corti; PLP-GFP, phospholipoprotein-green fluorescent protein; RF, radial fiber. Bar indicates 100 μm in A, B, D, 50 μm in C, E, F and 10 μm in G.