Gene expression molecularly defines the animal pole domain in the sea star. Embryos are shown laterally, with the animal pole up and oral side to the right. (A-F) WMISH. Expression of (A) foxq2, (B) pax6, (C) pea3, (D) zic, (E) rx and (F) six3 within the apical-most ectoderm defines the animal pole domain within late gastrulae (Figures 4A, 4D and 4F) and early larvae (Figures 4B, 4C and 4E). The vegetal limits of this domain are variable (see dotted lines in Figures 4E and 4F). Transcripts of pea3 additionally localize within the ectoderm of the larval ciliary bands (arrows in Figure 4C). pax6 expression in mesodermally derived coelom (arrow in Figure 4B). (G) FISH demonstrates that the ciliary bands, as marked by foxg (red), run through the ectoderm of the animal pole domain, as marked by pax6 (green). Colocalization is shown in yellow.