Figure 5.

Cochlear nucleus defects in a subset of Sef mutant mice. a, Diagram of the mouse auditory brainstem. Information arrives from the inner ear via the eighth nerve. Spiral ganglion axons (green) connect to a variety of cell types in both divisions of the cochlear nuclei. A major population of neurons in AVCN (purple) projects to the superior olivary complex both ipsilaterally and contralaterally; other pathways are not shown. The dashed box indicates the region shown in b–d. D, Dorsal; L, lateral. b–d, A Nissl-stained section in the coronal plane through a wild-type brainstem (b) illustrates the normal anatomy of the cochlear nucleus. Abnormal morphology was observed bilaterally in one mutant (c) and unilaterally in one heterozygote (d). AVCN is misshapen and fails to separate from the surrounding tissue. The cerebellum has overgrown its normally free lateral edge (d). cb, Cerebellum; 8th n, eighth nerve. Scale bar, 100 μm.