Fig. 2. 1E11 and serotonergic immunoreactivity of Stichopus japonicus from late gastrula to early auricularia larvae. (A–D) Late gastrula. 1E11 immunoreactivity was
first observed in some cells at the anterior tip of the late gastrula stage (B). Some of the 1E11-positive cells were also positive with the serotonin antibody (B–D). One
of them is marked with arrowheads (B–D). The anterior regions of the embryos are enlarged in the inset (B–D). (E–I) Early auricularia. 1E11-positive cells were
present in the oral hood (F). Some cells also showed serotonergic immunoreactivity (G, H). Pseudopod-like processes extended from some of the 1E11 reacting cells in
the oral hood (I, arrows). (A, E) Nomarski DIC images. Scale bars: A, E: 50 μm, I: 10 μm.