Fig. 5. fng is required to specify polar cells. fng¹³ clones marked with -Myc (green) and stained for nuclei (white) and Fas III (red). Arrows indicate polar cells; arrowheads point to the absence of polar cells. (A) Stage 2 follicle with fng⁺ main-body follicular cells and fng^- stalk cells, A" is a Nomarski image. Brackets indicate abnormal stalks. (B) Stage 6 follicle with fng^- cells at the anterior and no anterior Fas III-positive cells. The more anterior follicle (partially visible) has only two fng⁺ cells at its posterior (staining intensity enhanced in inset); they are polar cells and the follicle appears normal. (C) Stage 7 follicle with fng^- main-body follicle cells and fng⁺ polar cells. The image is a composite from two different focal planes of the same follicle, fused at the broken line.