Fig. 2. The expression pattern of Mn1 mRNA along the anteroposterior axis of the developing palate. Middle palate corresponds to the palatal region flanked by the maxillary first molar tooth germs. (A-C) At E12.5, Mn1 mRNA expression in the developing secondary palate exhibits an anteroposterior gradient, with low levels in the anterior palate (A), moderate levels in the middle palate (B) and highest levels in the posterior palate (C). (D-F) At E13.5, Mn1 mRNA expression is still high in the middle (E) and posterior (F) regions, and much weaker in the anterior region (D) of the developing palate. (G-I) At E14.5, the bilateral palatal shelves have elevated to the horizontal position above the tongue and have initiated contact and fusion in the anterior (G) and middle (H) regions. Mn1 mRNA expression remains strong in the middle and posterior (I) palatal regions, and relatively weak in the anterior palate. p, palatal shelf; t, tongue.