Figure 3. tdTomato-labeled cells express markers of supporting cells.
Atoh1Cre*PR; R26RtdTomato cochlear explants established at E13, treated with 10 nM RU486 for the first 24 hours in culture, and maintained for 6 DIV. tdTomato-positive cells are shown in red, and HCs are marked with MyoVI or MyoVIIa (blue). Open arrowheads indicate tdTomato-labeled cells with SC morphology. A. Shallow confocal Z-stack projection of the lumenal surface of a cochlear explant. Three tdTomato-positive, MyoVI-negative cells are shown. B. F-actin-rich stereocilia bundles present on HCs are stained with phalloidin (green). C. Merge of (A) and (B). The tdTomato-labeled cells lack stereocilia bundles (open arrowheads). D. A single MyoVIIa-negative cell is present between the IHC and OHC rows (open arrowhead). E. Pillar cells are labeled with anti-p75NTR (green). F. Merge of (D) and (E). p75NTR labeling coincides with tdTomato staining. D′–F′. Z-stack confocal reconstructions from the images shown in (D–F). The XY location of the Z-stack is indicated by the brackets in (D–F). The p75NTR and tdTomato-positive, MyoVIIa-negative cell has characteristic PC location and morphology. G. Several tdTomato-positive, MyoVIIa-negative cells in the OHC or PC region (open arrowheads), or IHC region (arrow) are shown. H. Anti-Prox1 staining in the nuclei of SCs in the OHC and PC regions (green). I. Merge of (G) and (H). tdTomato-labeled cells found near OHCs and PCs are Prox1-positive (open arrowheads), but a labeled SC adjacent to the IHCs is Prox1-negative (arrow). J. Z-stack confocal reconstruction showing two tdTomato-positive SCs. K. S100A1 marks the IHCs, PCs, and Dieters’ cells (green). L. Merge of (J) and (K). The SC next to the IHCs is S100A1- negative (arrow), but the tdTomato-positive outer PC is S100A1-positive (open arrowhead).