Fig. 6. Expression of At.fkh transcripts revealed by whole-mount in situ hybridization. (A) Stage 4 embryo viewed from the top of the germ disc. fkh transcripts are found around the blastopore (white arrow). (B) Early stage 5 embryo. Expression of fkh transcripts are seen in cells dispersing from the center of the germ disc and in cells encircling the germ disc. (C,D) Mid-stage 5 embryo flat mounted. (D) High magnification of the boxed area in C, focused on the mesenchymal cell layer. The At.fkh-positive cells are mesenchymal cells located below the surface epithelial cell layer. (E,F) Late stage 5 embryo. The cumulus is magnified in F. In addition to the dispersing mesenchymal cells and the peripheral cells, expression of fkh transcripts is observed in epithelial cells at the cumulus (arrow in E). (G,H) Stage 6 (G) and 7 (H) embryos. Expression of fkh transcripts is observed in the emerging dorsal region of the embryos (arrows), where the At.fkh-positive cells appear to spread over the yolk. The peripheral At.fkh-positive cells appear to migrate circumferentially to the emerging anterior region of the embryo (H, a). a, anterior; p, posterior; v, ventral.