Sox2 is weakly expressed in FGFR1 signalling mutants at the onset of sensory cell differentiation.

<p>(A–C) At E14.5, Sox2 expression can be detected in the prosensory domain of control cochlear duct sections (A), but is down-regulated in <i>Six1enh21-Cre::Fgfr1^flox/flox</i> inner ear (B) and <i>Fgfr1</i>^{Δ<i>Frs/</i>Δ<i>Frs</i>} inner ears (C) (brackets). (D) Quantification of relative mRNA level of <i>Sox2</i> in E14.5 cochlear epithelial cells using quantitative PCR. Mean ± SD are shown. *<i>p</i><0.05. (E) The number of Sox2-positive cells from the middle turn of cochlear duct were counted. Mean ± SD are shown. Scale bar: A–C; 75 µm (in C).