Fig. 1. Development of the craniofacial primordia. (A-D) A frontal view of the prominences that give rise to the main structures of the face. The frontonasal (or median nasal) prominence (red) contributes to the forehead (A), the middle of the nose (B), the philtrum of the upper lip (C) and the primary palate (D), while the lateral nasal prominence (blue) forms the sides of the nose (B,D). The maxillomandibular prominences (green) give rise to the lower jaw (specifically from the mandibular prominences), to the sides of the middle and lower face, to the lateral borders of the lips, and to the secondary palate (from the maxillary prominences).