Ouabain Does Not Induce Selective Spiral Ganglion Cell Degeneration in Guinea Pigs

Figure 4

Examples of the variety in histological changes in the cochlea after round window membrane application of ouabain in guinea pigs. Cochleas in Category 1 do not demonstrate any effect of ouabain upon the OHCs (arrows), IHCs (arrow heads), SGCs, or the stria vascularis. These cochleas do not appear different from the left (nontreated) cochleas or from the right cochleas treated with lower ouabain concentrations (0.1 mM and 0.01 mM) or PBS alone. Category 2 contains cochleas with complete OHC loss, with apparent loss of peripheral processes in the osseous spiral lamina (), but without obvious loss of SGCs, in the basal and middle turns, while cochleas in Category 3 show complete OHC loss in all turns together with loss of peripheral processes in the osseous spiral lamina, which seem to be substituted with fibroblasts (), and extensive loss of SGCs in the basal and middle turns. In none of the animals, any loss of IHCs or histological changes in the stria vascularis are obvious. Scale bars: 50 μm (organ of Corti) and 100 μm (spiral ganglion and stria vascularis).