Fig. 5

Sketch drawings of Pax2/5/8 expression in Acanthochitona crinita, Nucula tumidula, and Idiosepius notoides. Dorsal (d)–ventral (v), apical (a)-abapical (aa), and anterior (ant)-posterior (p) axes indicate the orientation. Mouth is marked by asterisk in all panels. Pax2/5/8-expressing cell groups are indicated by red numbers in early trochophore larvae of Acanthochitona crinita (first row). Additional Pax2/5/8-expressing cells are located in the hyposphere of further developed larvae (second row). A pericalymma larva (third row) and a settled individual (fourth row) of Nucula tumidula express Pax2/5/8 in the mantle. Note that Pax2/5/8 is not expressed in the test cells (tc) that constitute the outermost cell layer. A stage 19 individual (fifth row) and a stage 24–25 individual (sixth row) of Idiosepius notoides express Pax2/5/8 in various domains. Red dashed line indicates trajectory of esophagus and internal yolk. Abbreviations: an, anus; at, apical tuft, ey, eye; f, foot; fn, funnel; g, gill; ib, interbasal lobe; m, mantle; ms, middle subesophageal mass; s, shell; sc, statocyst; sg, shell gland; se, supraesophageal mass; stm, stomach; ps, posterior subesophageal mass; pt, prototroch; y, yolk. Scale bars: 50 μm (except both last scale bars for I. notoides with 150 μm)