Fig. 2. Fgf8 and Fgfr3 are expressed in the developing organ of Corti. In situ hybridizations for Fgf8 and Fgfr3 were performed on E16 (A-D) and P0 (E-G) mice. Fgf8 is not detected at E16 in the apical region (A), but is seen in developing IHCs at the base (B, arrow). (C) At E16, Fgfr3 is faintly detected in a group of cells near the apex (indicated by brackets) and shows more robust expression within a similar region at the base (D). (E) Expression of Fgf8 at P0 is in the IHC (arrow), whereas Fgfr3 (F) is restricted to PCs (arrow) and DCs. (G) Whole-mount of the lumenal surface at P0 illustrating expression of Fgf8 in all IHCs. Scale bars: 30 µm in A-F; 20 µm in G.