Fig. 4. Upd-dependent internalization of Dome. From stages 4 to 10, endogenous Dome (in red) is detected in intracellular vesicles. (A,B,B') In early stages, vesicles are present in all follicle cells (A is a stack of several optical sections; B,B' represent an optical section through a stage 4-5 egg chamber), but later, they become restricted to the poles of the egg chambers (C,F-I), where the Upd ligand is most concentrated. (C-E) BCs contain a high level of Dome vesicles before, during, and after migration. (G,I,F,H) Dome is expressed in a gradient (represented by the white wedges) of apically located vesicles at the anterior (G,I) and posterior poles (F,H). (B,H,I) Vesicles contain the Dome protein, since they are absent in dome mutant follicle cells (broken outlines) at any stage. (J-L) Ectopic expression of the Upd ligand in main body follicle cells (J,K) or BCs (L) causes the accumulation of extra Dome-containing vesicles.