Secondary Degeneration of Auditory Neurons after Topical Aminoglycoside Administration in a Gerbil Model

Figure 4

Histologic analysis of the OC and SGCs at four different parts of the cochlea at 4 weeks after drug administration. At 4 weeks after drug administration, OC was intact in both KP and KG groups, but the KG group showed a flat epithelium without any sensory cells at all parts except the high middle part. In the KG group, a damaged spiral limbus (black arrowhead) was found at the high basal part. The KI group also showed severely damaged OC at all parts of the cochlea. The KG group showed no reduction of SGC density, showing a similar result to the control group. The KG group showed sparse SGCs at low middle, high basal, and low basal parts of the cochlea. The KI group showed sparse SGCs at all parts of the cochlea. The three groups were kanamycin percutaneous (KP), kanamycin gelfoam (KG), and kanamycin RW injection (KI). Scale bar represents 100 um.