Fig. 1

The embryonic origins of the jaw are highly conserved across amniotes despite species-specific differences in form and function. a Schematic transverse section through the midbrain-hindbrain boundary of a generalized amniote after neurulation showing the major lineages of cells and their cell types, cell–cell interactions (vertical arrows), and tissue derivatives that contribute to the jaw apparatus. b Head and jaw skeleton of a generalized vertebrate embryo showing the spatial arrangements of the neurocranium, viscerocranium, and dermatocranium. The neurocranium forms first as cartilage and surrounds the brain and sense organs such as in the nasal, optic, and otic capsules. The viscerocranium is the cartilaginous skeleton of the jaws and of the serially repeated arches (numbers 1 to 7) along the pharynx. The first arch is the mandibular arch, which consists of the palatoquadrate cartilage above and Meckel’s cartilage below. The second arch is the hyoid arch. The dermatocranium consists of the palatal, cranial vault, and tooth-bearing elements around the oral cavity. The viscerocranium is derived almost exclusively from NCM whereas the neurocranium and dermatocranium arise from both NCM and mesoderm