The structures for the face stem from various primordia around the stomodeum that have arisen up to the tearing of the oropharyngeal membrane (stage 11, ca. 29 days):

• a medial sacculation in front of the oropharyngeal membrane as the primordium of the adenohypophysis.
• the medial frontonasal process (processus frontonasalis) that soon forms a medial and a lateral nasal process on both sides and pushes the adenohypophysis into the stomodeum.
• the bilateral mandibular arch (first pharyngeal arch) with a maxillary and a mandibular process.