Figure 5.

Parvalbumin immunofluorescence resolves the disruption of the type II SGN fibers (outer spiral fibers) within the outer spiral bundles (OSB) of the PrphKO mouse cochlea. Examples of batch-processed cryosections from WT (A,C) and KO (B,D) cochleae delineate the terminal regions of the outer spiral fibers, particularly with respect to their migration along the medial aspect of the Deiters' cells (DC) up to the base of the outer hair cells (OHC). Parvalbumin was also strongly labelled in the inner hair cells (IHC) in the basal region of the cochlea (C,D), and in type I SGN afferent fibers within the inner spiral plexus (ISP). There was a much higher density of outer spiral fiber labeling at the level of the OSB in the WT tissue (filled arrowheads) compared with the KO tissue (open arrowheads), consistent with the β-III tubulin and NF200 immunolabelling experiments. The medial olivocochlear efferent projections to the OHCs are not delineated by this parvalbumin immunolabelling. Apical and basal regions from the same cochlea for each of WT and KO.