The ultrastructure of the differentiating pupal leg ofDrosophila melanogaster.

The ultrastructure of the developing pupal leg ofDrosophila melanogaster is investigated at various stages from white prepupa to pharate adult. All the different cell types found in the leg at each stage examined are traced developmentally. This includes general epithelium which secretes both a pupal and adult cuticle and specialized epithelial structures such as apodemes, bristles and other sense organs. Muscle, nerve and tracheal tissue develop within the leg cavity. Particular attention was paid to the development of muscle tissue which was shown to differentiate from the adepithelial cells of the larval disc. The development of theDrosophila leg is compared with that ofCalliphora (van Ruiten and Sprey, 1974) especially with respect to the different stages at which new structures appear in the two species.