Mutual repression between Gbx2 and Otx2 in sensory placodes reveals a general mechanism for ectodermal patterning

► Otx2 and Gbx2 segregate placode progenitors of different fates. ► Otx2 and Gbx2 mutually repress each other. ► Otx2 target activation is required for olfactory, lens and trigeminal specification. ► Gbx2 is required for otic placode specification.