Fig. 1. Drosophila wing disc and fate maps. (A) Third instar wing disc. To generate the wing/hinge and body wall fragments, the discs were cut across above the folds corresponding to the hinge region (arrowheads). (B) Fate map of the wing disc showing the anterior-posterior (AP) and dorsal-ventral (DV) compartment boundaries and major regions in the disc. In the adult, the wing pouch (green) gives rise to the wing blade, the hinge (yellow) constricts to form a mobile link to the body wall (blue) or mesonotum of the fly. (C) Cell layers of the wing disc. There are three cell layers: the squamous epithelium or peripodial membrane, the columnar epithelium that gives rise to the adult epidermis, and the adepithial layer comprised of myoblasts, which develop into the flight muscles of the thorax, and tracheal cells of the larval and future adult airways.