Figure 7. ATOH1 protein expression.
A. Section from the base of an E14 cochlea. Three ATOH1-positive nuclei are present (red, arrows). B–F, I. Sections from cochleae at the indicated ages, stained with antibodies against ATOH1 (red) and MyoVI (green). F-actin stained by phalloidin is shown in blue. B, C. E16 cochlea. Strong staining for the ATOH1 antibody is present in all HCs (also positive for MyoVI), at both the apex and the base. D–F. P0 sections. D. Low magnification view of two turns of the cochlea. MyoVI staining marks HCs in the apex and base (arrows). Non-specific background staining from the ATOH1 antibody is present on the surface of the stria vascularis (open arrowheads). E. Apical section from (D). Strong ATOH1 signal is present in the OHCs (bracket), but slightly weaker staining is found in the IHC (arrow). F. ATOH1 staining is almost absent in a section from the base at P0 in both the IHC and OHCs. G, H. In situ hybridizations for Atoh1 transcript. Atoh1 mRNA is still present at the apex (G) and base (H) of a P0 cochlea. I. ATOH1 protein is not detectable at the apex of the cochlea by P5. J. ATOH1 protein (red) in the mid-base of an E16 Atoh1+/+ cochlea. K. Same section as in (J), also showing MyoVI staining (blue), weak Sox2 staining in the HC nuclei, and strong Sox2 staining in the SC nuclei (green). L. In a section from an E16 Atoh1−/−cochlea, no reactivity for either ATOH1 (red) or MyoVI (blue) is visible. Sox2-positive cells remain (green). M. Relative expression levels of Atoh1 and MyoVI in the cochlear epithelium at E13, E15, P0, and P5 as determined by qPCR. Values are presented as relative to E15. Error bars represent SEM. *p<0.01.