Figure 4

Expression of IRF6 in the developing chick embryo. Expression is restricted to facial ectoderm. Whole-mount in situ hybridisation (a, c, e) and vibratome sections of whole-mount embryos (b, d) revealed notable IRF6 expression in the epithelia surrounding the frontonasal process, the maxillary primordia, and the nasal pits. IRF6 expression was also detected in the ectoderm of the leading edges of the palatal shelves and in the ridges of the primitive oral cavity at HH30 (h). High IRF6 expression was also found in the apical ectodermal ridge of the limb buds (g) and in the egg tooth primordium (f).