Fig. 9

24-h larva. a Single SBSEM scan through the level indicated by the arrow in Fig. 8a showing structures on the left side. Scale bar = 5 μm. b Enlargement of a showing Hatschek’s nephridium, including a flagellar/microvillar process (arrow). Scale bar = 2 μm. c 24.5-h larva. Conventional TEM cross section at the level of the arrowhead in Fig. 8a. The asterisk indicates the region of body wall where pharyngeal endoderm cells are contacting the ectoderm. Scale bar = 10 μm. d Enlargement of the cells nearest the asterisk in c; pharyngeal endoderm cell (toward left) extends basally to contact an ectoderm cell (toward left). Scale bar = 2 μm. e The basal region of pharyngeal endoderm cell in d associated with an ectoderm cell at the left. Scale bar = 1 μm. f The apical region of pharyngeal endoderm cell in d associated with an adjacent endoderm cell by an inconspicuous intermediate junction (arrow). Scale bar = 1 μm. ect, ectoderm; Hn, Hatschek’s nephridium; lpm, lateral plate mesoderm; no, notochord; om, oral mesoderm; pe, pharyngeal endoderm; om, oral mesoderm; sls, second left somite