Wing disc development in the fly: the early stages.

The establishment of the wing anlage in Drosophila is dependent on the presence of two organizing centers located at the boundaries of the dorsoventral and anteroposterior compartments. How these boundaries are defined was not understood until recently. Furthermore, nothing was known about how the hinge region of the wing is defined. Recent data have now started to provide some insight in the molecular processes required for the definition of the major boundaries and subdivision of the wing anlage into the hinge and blade region.