Fig. 3. fng expression. (A-D,F,J,K) fng expression shown by in situ hybridization. (E,G,I) X-gal staining in fng-lacZRF584. (H) Serrate expression shown by antibody staining. Arrows point to polar cells. (A,B,E) Germaria, with different regions, as defined by morphological criteria (King, 1970; Spradling, 1993) indicated by roman numerals. Arrowhead in B points to the IIb-III border. (C,D) Stage 3 (C) and stage 5 (D) follicles with fng expression restricted to polar cells. (E) Germarium, followed by stage 2 and 3 follicles. (F) Stage 7 and 8 follicles with fng expression in posterior cells that contact the oocyte. (G) Polar and stalk cells between stage 2 and 3 follicles express fng. (H) Serrate is expressed in all somatic cells during follicle formation. (I) Stage 7 follicle with fng expression in anterior and posterior polar cells. Expression in other posterior cells is present (bracket). No expression is detectable in germline cells. (J) Stages 7 and 9 follicles. At stage 9, fng is expressed in follicle cells that migrate towards the oocyte (bracket). Among the border cells, fng is expressed only in polar cells (arrow). (K) Stage 10b follicle; antero-dorsal follicle cells do not express fng (asterisk).
