FIG. 7.

Sox2 labeling in adult mouse cochlea. These confocal images were taken from whole-mount preparations of the apical turn of adult mouse organ of Corti that were immunolabeled for parvalbumin (green) and Sox2 (red). The nuclei were counterstained for bis (blue). The images are brightest point projections from Z series stacks parallel to the reticular lamina (step size of 1 μm). A–B Apical turn from a normal undamaged organ of Corti. In part (A), all three channels are shown, whereas in (B), only the red channel with the Sox2 label is shown. Inner and outer hair cells are present, and they are labeled by parvalbumin which labels the HC cytoplasm. The transcription factor Sox2 is undetectable in HC nuclei. The arrow points to an individual OHC, and the bracket delineates the OHC region. Sox2 labels the nuclei of all organ of Corti support cell types. C–D Apical turn from a drug-damaged mouse organ of Corti (one set of kanamycin and furosemide injections and 2 days of recovery). All three channels are shown in part (C), whereas only the red channel with the Sox2 label is shown in part (D). Inner hair cells are present in the tissue, and the arrow points to a rare remaining OHC. The bracket delineates the OHC region. Virtually all of the OHCs are missing. Sox2 labeling is retained by all SCs in the damaged cochlea. Scale bar is identical for panels (A–D) and equals 20 μm.