Fig. 6. Polar cells localize the oocyte and establish the AP axis. (A,B) fng mosaic follicles stained with Hoechst (DNA, white) and antibodies recognizing -MYC (wild-type cells, green) and FasIII (polar cells, red). (A) Stage 6 follicle with no posterior polar cells; the oocyte (asterisk) is at the anterior, in contact with the anterior polar cells (arrow). (B) Stage 5 follicle with ectopic lateral polar cells and no posterior polar cells. The oocyte (asterisk) is ectopically localized, in contact with the lateral polar cells (arrow). (C,D) Germaria stained with phalloidin (F-actin, blue) and antibodies recognizing Bic-D (oocyte, red). (C) Wild type. At stage 1, the oocyte (arrow) is located at the posterior of the cyst (D) fng mosaic marked with -MYC (fng⁺ cells, green). In a stage 1 mutant follicle, the oocyte (arrow) is in the center of the cyst. (E,G,I) Wild-type follicles and (F,H,J) fng mosaic follicles stained with X-gal (blue/turquoise, pnt^S99812 in E,F; kin:lacZ in G,H; nod:lacZ in I,J) and antibodies recognizing FasIII (polar cells, black/brown). In F,H,J, the polar cells (arrow) are ectopically localized to the side of the follicle, but (F) the follicle cells surrounding them adopt a posterior identity, and (H,J) the AP axis of the oocyte (asterisk) is correctly oriented with respect to the polar cells.