Schematic
showing the site of horseradish peroxidase (HRP) injection to label type II
fibers in the spiral ganglion of the cochlea. Auditory nerve fibers are
shown peripherally in the cochlea where type II fibers form the afferent
innervation of the outer hair cells (OHC) and type I fibers form the
afferent innervation of the inner hair cells (IHC). Both fiber types project
centrally in the auditory nerve, bifurcate in the cochlear nucleus, and form
branches in the anteroventral, posteroventral, and dorsal subdivisions of
the cochlear nucleus (AVCN, PVCN, and DCN). Dividing the VCN from the DCN is
the granule-cell lamina, a region of termination for many type II fibers.
Type II fibers in the lamina were examined in the approximate location
indicated by the dashed box. The figure orientation is approximately the
sagittal plane (see compass indicating dorsal toward the top of the figure).
In successive figures, the orientation is reversed (dorsal toward the bottom
of the figure) in order to be consistent with our previous work (Brown et
al. 1988b; Benson and Brown
1990; Benson et al.
1996).