Fig. 1. An ovariole, and early acquisition of cell fates in the follicle cells. The germarium is at the anterior (left, upper bracket), and progressively older egg chamber stages (Spradling, 1993) develop to the posterior (right). Somatic stem cells (blue) produce follicle cell precursors (brown), which form main body precursors that express EYA (brown) and polar/stalk cell precursors (yellow) that ultimately eliminate EYA expression. Main body cells differentiate at stage 6 (light brown). Unpaired is emitted from the polar cells (red) and received by STAT in the stalk cells (green). Polar, stalk and main body cells are all thought to require the activity of Notch (N) for differentiation. NC, nurse cells; FC, follicle cells; O, oocyte.