Wnt pathway over-activation induces A/P axes duplication and elongation. (A) Upon chemical treatments with Wnt pathway agonist (LiCl), in some cases, single individuals within a colony showed signs of axes duplication (double arrows). At N + 2 cycle, next to the adult bifurcated individual, only primary buds are visible (single arrows). (B) Dorsal view enlargement of one of the zooids in (A) showing a double oral siphon. (C) Toluidine blue staining of semi-thick sections (150 μm) from control colony indicating the A/P axes orientation on primary (B - blue) and secondary (b - yellow) buds. (D) The same preparation on drug-treated colony shows bifurcated peribranchial epithelium within the budding region. BAR: 1 mm (A); 200 μm (B); 500 μm (C and D).