Histological evaluation of cochlea fromIdh2+/+andIdh2−/−mice. H&E staining was performed in the inner ear sections of Idh2+/+ and Idh2−/− mice at 2 months of age. SG, spiral ganglion; SV, stria vascularis; SL, spiral ligament. Scale bars, 100 µm in (i′) and 20 µm in (c′ and f′). The arrowheads point to three rows of outer hair cells, and the asterisk (*) indicates an inner hair cell.