Hesr2 (A) Sox2 (B), Math1 (C) and Notch signaling components, Jag1 (D), Hes5 (E) in the E15.5 cochlea. Levels (half-turns) of the cochlear duct are numbered from base (1) to apex (4). Hesr2, Sox2 and Jag1 were expressed throughout (turn 1 to 4) the cochlea (arrowheads in A, B and D). Math1 and Hes5 were also expressed in the basal turns (arrowheads in C, E) but not in the apical turns (open arrowheads in C, E). Scale bar= 100 µm.