Fig. 5. foi RNA expression pattern. Embryos labeled by in situ hybridization revealing the foi RNA expression pattern (purple). (A) Stage 3 embryo. The maternal foi RNA has almost completely disappeared except for in the pole cells (posterior, right). (B) Stage 6 embryo. foi is expressed generally but is enriched in the invaginating mesoderm. (C) Stage 9 embryo. Note the high levels of foi RNA in the anterior and posterior midgut primordia. (D) Stage 14 embryo. foi is broadly expressed, but only low levels are found in the epidermis.