HEDGEHOG, WINGLESS AND ORTHODENTICLE SPECIFY ADULT HEAD DEVELOPMENT IN DROSOPHILA

The adult head capsule of Drosophila forms primarily from the eye-ante nnal imaginal discs, Here, we demonstrate that the head primordium is patterned differently from the discs which give rise to the appendages . We show that the segment polarity genes hedgehog and wingless specif y the identities of specific regions of the head capsule. During eye-a ntennal disc development, hedgehog and wingless expression initially o verlap, but subsequently segregate. This regional segregation is criti cal to head specification and is regulated by the orthodenticle homeob ox gene. We also show that orthodenticle is a candidate hedgehog targe t gene during early eye-antennal disc development.