Foxg1 Organizes Cephalic Ectoderm to Repress Mandibular Fate, Regulate Apoptosis, Generate Choanae, Elaborate the Auxiliary Eye and Pattern the Upper Jaw

Gnathostome jaw patterning involves focal instructive signals from the embryonic surface cephalic ectoderm (SCE) to a fungible population of cranial neural crest. The spatial refinement of these signals, particularly for those patterning the upper jaws, is not fully understood. We demonstrate that , broadly expressed in the SCE overlying the upper jaw primordia, is required for both neurocranial and viscerocranial development, including the sensory capsules, neurocranial base, middle ear, and upper jaws. controls upper jaw molecular identity and morphologic development by actively inhibiting the inappropriate acquisition of lower jaw molecular identity within the upper jaw primordia, and is necessary for the appropriate elaboration of the λ-junction, choanae, palate, vibrissae, rhinarium, upper lip and auxiliary eye. It regulates intra-epithelial cellular organization, gene expression, and the topography of apoptosis within the SCE. integrates forebrain and skull development and genetically interacts with to establish a single, rostral cranial midline.