Fig. 4

Analysis of Pdu-Tcf expression. Images show virtual orthogonal sections through confocal fluorescent z-stacks of Pdu-Tcf in situ hybridization staining to illustrate inner features and expression domains. The stages are indicated; 48 and 72 hpf—coronal sections from ventral to dorsal; 5 and 7 dpf, top—coronal sections with the positions of transverse sections indicated; 5 and 7 dpf, from top to bottom—consecutive transverse sections from anterior to posterior as indicated by a yellow dashed line on the coronal sections. The approximate size of a 48 hpf larva is around 130 µm, and other images are to scale. Red asterisk—apical organ, red dashed line—stomodaeal rosette/pharynx (foregut), yellow arrow—segmental expression in chaetal sacs, yellow asterisk—eye-forming region, yellow dashed line—position of transverse sections, yellow line—midgut + hindgut or putative gut tissue. bgl brain ganglia, ch chaetae, chs chaetal sacs, fg foregut, hg hindgut, j jaws, mg midgut, sg spinning glands, vnc ventral nerve cord(s)