Figure 4

3D reconstruction of the embryo of Saccoglossus kowalevskii at early kink stage (~ 56 h pf). Rows from left to right: dorsal, ventral, left and right view. Columns from up to down: The merge row (A-D) shows the embryo with all reconstructed structures. Epidermis row (E-H) shows the external shape of embryo. The telotroch is not shown. Endoderm row (I-L) reveals the transparent endodermal tissue (light green) and the straight course of the endodermal lumen (yellowish green). Lateral evaginations (double arrowheads) in the collar region illustrate the connections to the pockets that constitute the mesocoela. Mesoderm row (M-P) shows the position of the anterior protocoel (blue) and the paired meso- (pink) and metacoelic (red) compartments. The anlage of the pericardium (purple) emerges in the posteriormost region of the proboscis (pr) within the ectoderm. Download interactive 3D-PDF as Additional file3. co collar, mo mouth opening, stA anlage of the stomochord, tr trunk.