Figure 4
The evolution of imaginal discs. The drawings show cross-sections through the body of the larvae. (a) In the basal species Anopheles gambiae the future appendages are present as pouches budding from the larval epidermis. The future dorsal notum develops from a group of cells at the border between the larval and wing bud epithelia. Reproduced from (Clements, 1992). (b) In cyclorraphous Brachycera, as shown here for D. melanogaster, the developing imaginal discs are embedded well inside the laval body and remain connected to the larval epithelium through long thin stalks. The thorax and the wing both originate from the imaginal disc.
