Fig. 1.

Overview of human craniofacial development and organ systems. (A) Pharyngeal arch stage (human 4-5 weeks) with cross-sectional diagrams illustrating the major germ layer contributions. Facial ectoderm, purple; cranial neural crest, green; pharyngeal mesoderm, red; pharyngeal endoderm, orange. (B) Contribution of germ layers to the bones and teeth of the face and skull (left), muscles and glands (right). (C) Developmental stages of a typical tooth, facial gland and palate. Germ layer contributions are shown for the tooth and gland.