(a, b) D. melanogaster eggshells have two oar-shaped DAs with long stalks and flat paddles. Dorsal and lateral views are shown, respectively. (c) Two pathways define the DA primordia by controlling expression of broad. EGF signaling regulates broad expression as a function of ligand (gurken) concentration (see text). DPP signaling acts in a negative feedback loop with Broad. (d, e, f) S. lebanonensis eggs have 4–8 long, thin DAs. (d, e) Lateral views of eggs with 4 DAs and 7 DAs, respectively. (f) Distribution of DA number; N = 539.