Fig. 3. Expression of At-sog, At-fkh and At-sim transcripts in embryos at late stage 9 (A,C,E) and stage 10 (B,D,F). (A,B) Embryos stained for At-sog. At-sog expression at the ventral midline area is lost from the medial part (A), splitting into two lines (B). (C,D) Embryos double-stained for At-sog (red) and At-fkh (purple). At-fkh expression is detected at the most medial part, complementary to At-sog expression (C). The At-fkh expression is mostly lost at the ventral midline area, but starts in a pair of cell clusters in every hemisegment (D). Note that the clusters are included in the lines of At-sog. Arrows indicate the expression at the stomodeum. (E,F) Embryos double-stained for At-sog (red) and At-sim (purple). At-sim expression is observed at the most medial part, similar to At-fkh expression (E), then it fades, leaving a pattern different from those of At-sog and At-fkh (F). All embryos were flat-mounted. Anterior is to the top. Ch, chelicerae; Pp, pedipalps; L1 and L2, first and second walking legs. Scale bar: 100 µm.