Figure 6.

Fgf20 rescued hair cells in addition to Sox2 at E13.5 + 5 DIV upon Notch inhibition. A–C, Merged images with Gfi1 (green) and Sox2 (red). A′–C′, Sox2 labeling alone. A″–C″, Gfi1 labeling alone. A‴–C‴, Higher magnification of apices (boxed areas in A–C, respectively). A, Control E13.5 explants show normal hair cell and support cell development has been completed up to the apex of the cochlea after 5 DIV. B, DAPT treatment of E13.5 cochlea revealed both lateral inhibition effects (arrow, B″) and prosensory inhibition at the apex. B′, B″, Sox2 is downregulated along the whole length of the cochlea while hair cells are formed at the expense of support cells. B‴, No hair cells or support cells were present at the apex. C, Fgf20 in the presence of DAPT rescued both Gfi1⁺ hair cells (green) and Sox2⁺ support cells (red). C′, Sox2 rescue was seen along the whole length of the cochlea. C″, Gfi1 rescue was seen in the mid-base to apex region of the cochlea with some sporadic rescue in the base. C‴, Both Sox2 and Gfi1 were rescued in the apex of the cochlea. Scale bars- 200 μm.