Figure 9. Efferent synapses are present in aged OHCs.
A and B, Maximum intensity projections of confocal z-stacks taken from the apical cochlear region of 6N (A) and 6N-Repaired (B) mice at 1 and 15 months of age using antibodies against SK2 (green) and ChAT (red). Myosin 7a (Myo7a) was used as a hair cell marker. Arrowheads indicate OHCs with only efferent terminals; and arrows indicate OHCs with only anti-SK2 signals. Scale bars: 10 μm. C, Number of SK2 puncta per OHCs present in a 140 μm apical cochlea region as a function of age in C3H, 6N, 6N-Repaired and 6J mice. D, Percentage of juxtaposed SK2 and ChAT puncta as a function of age and strain. Data are plotted as mean values (± S.D.) and individual OHC counts are indicated by the open symbols. Numbers below or above the data in panel C represent the number of mice and (OHCs) used for each time point, which also apply to panels D.