Development of Drosophila imaginal discs in vitro: Effects of ecdysone concentration and insulin

Abstract A detailed scoring system was used to determine the effects of a variety of factors on the evagination and differentiation of Drosophila imaginal discs cultured in vitro. In modified Schneider's Drosophila medium, β‐ecdysone induced development at concentrations approximately 100x lower than α‐ecdysone. The metamorphosis of imaginal discs consists of two processes, evagination and differentiation, which were found to be differentially sensitive to hormone concentration. Optimal differentiation occurred at relatively low β‐ecdysone concentrations (30 ng/ml), while complete evagination required higher levels (500 ng/ml). Even at the optimal hormone concentration for differentiation, not all discs differentiated completely, and each region of the eye, antenna, wing, and leg exhibited a characteristic frequency of differentiation. In addition, a strong negative correlation between the extent of evagination and the quality of differentiation was observed. Bovine insulin stimulated β‐ecdysone induced evagination, but at the same time it inhibited differentiation.