Figure 7.

The effect of a NeuroD null mutation on the pattern of innervation of the cochlea and vestibular system is revealed with Dil tracing and confocal microscopy. All vestibular and cochlear epithelia show hair cells, but some hair cells have no innervation. In the vestibular system, the utricle shows a somewhat disorganized innervation in the NeuroD mutant (B) but may lack all innervation of canal cristae (A, B). The cochlea shows a reduction in size and a loss of most spiral sensory neurons (C, D). The remaining neurons expand their peripheral processes to innervate most inner hair cells and a few outer hair cells. Bar indicates 1 mm (C, D) and 100 μm (A, B).