Figure 1.

Representative images of surface preparations from mid-cochlea (3 mm from the apex) of mice at 5-7 months of age (A), 22-24 months of age (B) and 27-29 months of age (C), co-labeled with phalloidin (red label) to image hair cells and scars in regions of missing hair cells and with CTBP2 immunolabeling (green puncta) to mark the ribbons in inner hair cell – auditory nerve synapses. Outer hair cell loss is seen at 22-24 months (B) and at 27-29 months (C) and not at 5-7 months (A). CTBP2 immunolabeling (green puncta) is seen at inner hair cell bases at all ages. Quantitative assessment of hair cell loss is seen in shown in Figure 2. Quantitative assessment of CTBP2 puncta (marker for ribbons and synapses) per inner hair cell is shown in Figure 4. Bar = 10 μm.