Drosophila Imaginal Discs as a Model System for the Study of Metamorphosis

Abstract

The essence of metamorphosis in insects comprises those developmental programs that dispose of or modify larval tissues and produce the form and function of adult tissues. In Drosophila these metamorphic programs are executed during two developmental periods, the so-called prepupal period, immediately following puparium formation, and the pupal period. During the prepupal period, the imaginal discs, the embryonic precursors of many adult cuticular structures, undergo morphogenesis to create the external form of the adult, including the head, legs, and wings. During the pupal period, internal adult structures develop—viscera, muscles, nerves—and the detailed external differentiation occurs to produce bristles, hairs, sensillae, and other components. Fortunately, the metamorphosis of imaginal discs occurs in vitro under defined culture conditions (Fristrom et al, 1977; Mandaron et al., 1977; Milner, 1977) to produce not only basic adult structures, e.g., legs and wings, but under optimal conditions even musculature and neural tissue and the fine sculpturing of bristles and hairs in their characteristic arrays (Mandaron et al, 1977; Milner, 1977)