Fig. 1. The JAK ligand, Upd, is expressed in the follicular epithelium. (A) Expression of upd in the vitellarium is restricted to the two polar cells at the anterior and posterior end of each egg chamber. Within region 3 of the germarium (B), upd is expressed in the most posterior follicle cells (arrowhead). (C) A schematic representation of upd expression (shaded) illustrates the expression in the polar/stalk cell precursors at the posterior of the germarium and the polar cells in the vitellarium. (D) Stat92E is expressed strongly in the follicle cells of the germarium and terminal cells of chambers of the vitellarium up to stage 4, then weakly in later stages.
