SEM and TEM of labelling in <i>Pcdh15</i>^{<i>+/av3J</i>} and <i>Pcdh15</i>^{<i>av3J/av3J</i>} mice.

<p>(a, b). SEM comparison of OHC hair bundles. The heterozygote is similar to wild type but the homozygote bundle is dysmorphic. Nevertheless the latter still has regions of ranked (r), as well as unranked (u) stereocilia. (c–d). Pre-embedding immunogold labelling using TEM in P3 heterozygote and homozygote hair cells at approximately 80% of the distance from the cochlear base. The heterozygote labelling resembles the wild type, but the homozygote shows predominant labelling on the unranked stereocilia. Note that lateral links occur between the unranked stereocilia, as well as the ranked stereocilia, and are still present in the homozygote (d, inset arrowhead, ultrathin section) where they are also labelled (arrow, main image). (e, f) Quantitative analysis of labelling on the heterozygote and the homozygote. Labelling is lower down the bundle in the homozygote compared with the heterozygote, and is more concentrated in the unranked stereocilia. The blue bars show the heights of the tall stereocilia, the red bar the heights of the ranked and unranked short stereocilia. (g). Relative proportion of total labelling over the unranked stereocilia in <i>Pcdh15</i>^{<i>+/av3J</i>} and <i>Pcdh15</i>^{<i>av3J/av3J</i>} mice OHCs. There is a significantly higher proportion on the unranked stereocilia in the homozygote, <i>p</i> < 0.05, Wilcoxon (Mann-Whitney) test. Scale bars: a, b = 1.5 μm; c, d = 500 nm.