Fig. 5

Expression of ptSoxN. Flat-mounted embryos at different stages of development after RNA in situ hybridization. a) ptSoxN expression is restricted to the presumptive neuroectoderm in the most anterior region of the germ band in stage 7 embryos (white arrow). b) At stage 8.2, expression is in the most anterior part of the embryo (black arrowhead) and in the ventral nerve cord appearing sequentially from anterior to posterior: white arrows indicate expression in clusters that will subsequently broaden. Expression in the posterior region adjacent to the SAZ is also observed (black arrowhead). c) At stage 9.2 expression is observed throughout the ventral nerve cord, with differentiating neural clusters indicated by arrows. Ch: chelicerae, L1 – L4: prosomal segments 1 to 4, O1 – O4: opisthosomal segments 1 to 4, Pp: pedipalps; SAZ: segment addition zone. Ventral views are shown for all embryos with the anterior to the left. Scale bars: 150 μm