Fig. 2. Pole cells located in the anterior half of the embryonic gonad develop into GSCs in the adult ovary. (A-D) Embryonic gonads viewed as superimposed DIC and EGFP images, showing representative locations of an EGFP-marked pole cell in the embryonic gonad. All gonads are oriented with anterior to the left and posterior to the right. The outline of the gonad is evident in DIC, with arrowheads pointing to the gonadal border to assist viewing. A marked pole cell (white spheres) is located at the anterior tip (A), anterior (B), posterior (C), or posterior tip (D). Dotted lines show the midline of the gonads. (E,G) An ovariole with one EGFP-labeled GSC (white arrow in G), as shown in DIC (E) and corresponding EGFP (G) images, from a female developed from an embryo with a marked pole cell located in the anterior half of the gonad. The EGFP-labeled GSC has produced multiple labeled germline cysts and egg chambers, which form an alternating pattern of labeled germline cysts and egg chambers in the ovariole. (F,H) An ovariole with both GSCs labeled by EGFP (white arrows in H), as shown in DIC (F) and corresponding EGFP (H) images, from a female developed from an embryo with a marked pole cell located in the anterior half of the gonad. The EGFP-marked GSCs have produced a continuously labeled string of labeled germline cysts and egg chambers in the ovariole. Scale bars: in A, 5 µm for A-D; in E, 20 µm for E-H.