Fig. 3.

Representative ×10 and ×40 (inset) light microscopy images of Rhesus monkey otolith end organ maculae. Normal ears (A and B) show utricular and saccular maculae with type I and II hair cells (HCs), intact stereocilia (inset), and presence of otoconia. In an ITG-only ear treated just 20 days prior to euthanasia, the utricular (C) and saccular (D) maculae both appear remarkably healthy, with minimal HC loss, preserved neuroepithelial height, and intact stereocilia and otoconia. This is in contrast to evidence of cristae injury from the same specimen in Figure 2D–F. In MVP-only ears (E and F), or those that received ITG injection followed by MVP implantation (G and H), preservation of HCs, stereocilia, and otoconia are again demonstrated. However, in an ear with surgical trauma to the saccule as a result of PSCC electrode insertion (F), thinning of the neuroepithelium and overlying otoconia, with decreased HCs and almost complete loss of stereocilia, is observed. MVP multichannel vestibular implant. Scale bars are 100 and 50 μm (inset). Specimens shown: MRH37x left ear for normal, M067RhF right ear for ITG-only, M0603163RhO left ear for MVP-only, and M067RhF left ear (G) and F32RhD right ear (H) for ITG + MVP.