Down-regulation of p63 in the medial edge epithelia allows periderm migration.

mKrt17-GFP transgenic mice were used for time-lapse confocal imaging of periderm migration during development of the secondary palate. (A-C) On a wild-type background, GFP-positive periderm cells migrate out of the midline seam (arrowed) to form the epithelial triangles on the oral and nasal surfaces as part of the process whereby mesenchymal continuity across the palate is achieved. (D-F) In contrast, in Tgfb3^-/- embryos, GFP-positive periderm cells fail to migrate out of the midline epithelial seam and the secondary palate remains cleft. (G-I) Reducing p63 dosage in Tgfb3^-/- embryos restores the migratory periderm phenotype allowing palatal fusion and rescuing the cleft palate phenotype (region of midline is arrowed). p: palatal shelves. The images are representative stills taken at the same Z position over a 24-hour culture period. The videos are provided as Supplemental Material, S1–S3 Videos.