Practice question

Specification of eye field within anterior neural plate depends on inhibition of Wnt and activation of fibroblast growth factor signaling that together induce Rx, Pax6, Six3, and Otx2 eye-field transcription factors. FGF signaling from anterior neural ridge and mesoderm promotes eye field maintenance suppressing telencephalic fate and maintaining proliferation. Wnt signaling must be repressed anteriorly; ectopic Wnt abolishes eye field, Notch modulates progenitor maintenance, Hedgehog ventralizes and splits field but not initial specification. Thus FGF pathway synergizes with IGF and BMP antagonists establishing competent eye field ready for evagination and development.