Fig. 7

24-h larva. 3-D reconstructions based on SBSEM sequences. a Left side view of a reconstruction of a region similar to Fig. 4c; individual cells are depicted for the oral mesoderm. Scale bar = 10 μm. b Same view as a, showing cells for the oral mesoderm; the nuclei of Hatschek’s nephridium and the more anterior mesoderm cells of the first left somite are show, respectively, in gold and pink. Scale bar = 10 μm. c Oblique view of the right anterior side of the larva showing nuclei for the first left somite and for Hatschek’s nephridium as well as the cells of the oral mesoderm, which tends to bulge outward through the lateral window in the subectodermal basal lamina (indicted by the parallel black traces). Scale bar = 5 μm. d Anterior view including nuclei of Hatschek’s nephridium (gold); the cells of the oral mesoderm (various colors) bulge laterally (arrowhead) and medially (arrow) in regions where the basal lamina (nor shown) has disappeared. Scale bar = 5 μm. e Anterior view comparable to d, but showing flagellar/microvillar processes (blue rectangles) and nuclei of the Hatschek’s nephridium (gold); basal laminae are indicated by the parallel black traces. Scale bar = 5 μm. fls, first left somite; fmp, flagellar/microvillar process; Hld, Hatschek’s left diverticulum; Hn, Hatschek’s nephridium; Hrd, Hatschek’s left diverticulum; lpm, lateral plate mesoderm; pe, pharyngeal endoderm; om, oral mesoderm; sls, second left somite