Fig. 2.

Ouabain treatment can eliminate 95 % of spiral ganglion cells (SGCs) while sparing the inner and outer hair cells. Parvalbumin3 (PV3: red) was used as an immunomarker for SGCs and hair cells, and anti-neurofilament (NF: green) was used to label the auditory nerve fibers (ANFs). In the normal ear (A), anti-NF shows the myelinated central and peripheral axons of ANFs as well as their unmyelinated terminals under the inner hair cells. In the ouabain-treated ear (B), only a few SGCs remain (red arrow) and the anti-NF shows mostly medial olivocochlear (MOC) neurons in the intraganglionic spiral bundle (green arrow). Sections are from the upper basal turn; ouabain treatment was 1 week prior to histological processing. Scale bar in B applies to both panels. C Spiral ganglion cell survival at 1 week post ouabain. Cell counts from ouabain-treated ears (n = 6) are normalized to place-matched counts from control ears (n = 6). Data are from ears selected to have near-normal DPOAEs and ABR thresholds near, or above, 80 dB SPL, as shown in Fig. 1.