Figure 1.

Overview on mouse sections used for this study. Top row: Hematoxylin/eosin-stained frontal sections though the heads of E13.5 (top left) and E14.5 (top right) wildtype embryos; level of posterior palate. The boxed areas correspond to the palatal region depicted in the following figures. At E13.5 the palatal shelves are vertically oriented on each side of the tongue, whereas at E14.5 the shelves have elevated above the tongue and meet at the midline epithelial seam. p, Palatal shelves; t, tongue; n, nasal cartilage; e, eye; b, forebrain. Bar, 600 μm. Bottom row: schematic drawings of midsagittal sections through the heads of E13.5 (left) and E14.5 (right) wildtype mouse embryos. The two frontal section planes used in this study are indicated by dashed lines: a, level of anterior palate; p, level of posterior palate. Green, nasal cavity; red, tongue; ocre, brain; blue, elevated palate (E14.5).