Fig. 4

Wnt expression in B. lanceolatum is complex and spatio-temporally dynamic. Color-coded horizontal bars represent the expression domains of Wnt genes (see left box) and refer to schematic illustrations of B. lanceolatum embryos from blastula to early larva (lateral view at the top and dorsal view at the bottom; anterior is to the left and posterior to the right; main structures are labeled), organized by germ layer into endoderm (yellow), mesoderm (red), chordamesoderm (magenta), and ectoderm (dark blue, neural derivatives; light blue, epidermal derivatives). Vertical dotted lines delimit antero-posterior reference domains and underscore hypothesized Wnt functions during neural regionalization, posterior growth, and structure differentiation. The hash sign denotes minor differences with B. floridae expression. Abbreviations: ec ectoderm, men mesendoderm, ep epidermis, ch chordal plate, np neural plate, no notochord, cv cerebral vesicle, fo foregut, nt neural tube, so somites, hi hindgut, tb tailbud, pp. preoral pit, es endostyle, csg club-shaped gland, gs gill slit primordium, my myomere, mec mesothelial cells, fi fin, mo mouth primordium. See text for further details