Fig. 6. LR placement of the adult rudiment in the late pluteus H. pulcherrimus larvae from which part of the tissue lateral to the midplane, including the archenteron and the ecto-mesodermal tissues, has been removed in the mid-late gastrula stage. The larvae are viewed from the dorsal side, with the oral side at the top. The left and right sides of the larvae correspond to those of the viewer. (A) An eight-armed pluteus larva of H. pulcherrimus subjected to the right EME cut in the gastrula stage, as shown in Fig. 5A,B. The adult rudiment has formed on the right side of the larval body (arrow). (B) A control S. mirabilis larva in the early stage of adult rudiment formation. A vestibule (large arrow) and a hydrocoel (small arrow) have formed on the left side of the larva. There are no marks for vestibule formation in the ectoderm (large arrowhead) and for hydrocoel formation in the right coelomic sac (small arrowhead) on the right side of the larva. (C) An S. mirabilis pluteus larva in the early stage of adult rudiment formation that was subjected to the right EME cut in the gastrula stage. A vestibule (black arrow) and a hydrocoel (white arrow) have formed on the right side of the larva. Note that there are no marks for vestibule formation in the ectoderm (black arrowhead) or for hydrocoel formation in the left coelomic sac (white arrowhead) on the left side of the larva. (D) A six-armed pluteus H. pulcherrimus larva from which the tissue on the right vegetal side has been removed in the mid-late gastrula stage as shown in Fig. 5D,E. A vestibule (large arrow) and a hydrocoel (small arrow) have formed on the left side of the larval body. The right postoral arm did not regenerate and is absent, whereas the left postoral arm (arrowhead) is intact. Scale bars: 100 µm.