MBP and P0 expression are reduced in the cochleae of Tmprss1−/− mice. MBP (A) and P0 (B) expression in the auditory nerve of wild-type mice. C: Superimposition of A and B. P0, MBP and tyrosine kinase receptor B expression in the Rosenthal’s canal of adult wild-type (D, F, and H, respectively) and adult Tmprss1−/− mice (E, G, and I, respectively). D and E: Arrows indicate a spiral ganglion neuron fiber (D and E) and a spiral ganglion neuron body (F and G). The bony boundary of the Rosenthal’s canal shows strong nonspecific staining (G). P0 expression in the osseous spiral lamina and fibers projecting to auditory nerve in the brainstem of adult wild-type and adult Tmprss1−/− mice (J and K, respectively, and L and M, respectively). Scale bar = 20 μm, except in A, B, C, L, and M, where scale bar = 50 μm. Glial transition zone (gl) is approximately outlined by the white dotted line. osl, osseous spiral lamina; SGN, spiral ganglion neuron; AN, auditory nerve; IHC, inner hair cell; OHC, outer hair cell.