(A) Scheme showing targeting of the dorsolateral wall of the otocyst by electroporation of Pkiα and Gfp and (A’) a transverse section 12 hours after transfection with Gfp. (B) Detection of pCREB in sections of chick otocysts collected 12 hours after overexpression of Gfp alone, or of Pkiα and Gfp. n=11 embryos analyzed for both controls and experimentals. Boxes show regions enlarged below. Graph shows the mean value of pCREB signal intensity (unit: 8-bit gray scale value; minimum: 0, maximum: 255) that was assessed specifically in transfected (GFP positive) cells. (C) Reconstruction of serial sections of chick inner ears collected 5-6 days after Pkiα overexpression. Frontal (top single panel) and lateral (bottom paired panels) are shown. n=6 embryos sectioned; n=1 embryo reconstructed. (D-F) ISH of sections of chick otocysts collected 12-16 hours after Pkiα overexpression showing Pax2, Otx2, and Hmx3 expression. n=6 for both control and experimental embryos for each gene. Boxes show regions enlarged below, with borders of selected cells outlined. Arrowheads indicate the boundary of the dorsal Otx2- and ventral Hmx3-expression domains.