Figure 3.
Morphological consequences of transient nerve terminal impairment. Electron microscopy observations of vestibular nerve terminals at type I (hcI; top) and type II (hcII; bottom) hair cells in the peristriolar region of utricles from adult rats in given conditions are shown. A, B, Illustration of intact nerve calyx, afferent, and efferent bouton terminals in control utricles. C, D, Forty-eight hours after kainate application, both calyx and bouton terminals displayed characteristic swellings. The calyx membrane often came off from the hair cell membrane (arrows). Bouton swellings resulted in indentations of type II hair cell basal membrane. E–H, No damage persisted in the sensory epithelium 1 week after kainate application (E, F) or if DNQX was applied with kainate (G, H). nc, Nerve calyx; a, afferent; e, efferent; sc, supporting cells. Scale bars, 1 μm.