Expression of Hes6 in the presumptive hair cell precursors. In the cochlea, the primordial organ of Corti at E14.5 is marked by the expression of p27Kip1 (A, indicated by brackets). Adjacent sections were stained for an antibody against Math1 (B–C) or probed with a Hes6 antisense probe (D–F). The basal, medial, and apical regions of the cochlea are indicated. The arrows and arrowheads indicate the expression of Math1 and Hes6 in the presumptive inner and outer hair cell regions, respectively (B–F). SG: spiral ganglion. Scale bars: 50 μm.