Figure 1.

Ciliary band and ciliary band neurons in the sea urchin pluteus larvae. (A) Schematic diagrams of ciliary band in the larva. Green lines show ciliary band between oral ectoderm and aboral ectoderm, and magenta and orange dots show ciliary band neurons and lateral ganglia. m, mouth; a, anus. (B) The entire nervous systems of the pluteus larva revealed with a pan-neural marker, anti-synaptotagmin (1E11). Arrowheads show the two axonal tracts underlying the oral ectoderm at the base of the postoral arms. (C–E) Double staining using anti-goosecoid (C; Gsc) for oral ectoderm and anti-Hnf6 for ciliary band (D, E). Green dots outside of the band are non-specific signal produced by the Hnf6 antibody. The ciliary band lies adjacent to the oral ectoderm, but never overlaps. (F–G) Double staining with anti-synaptotagmin and anti-Hnf6. Magnified image for the rectangle in (G) shows the detail of this co-localization (H–K). The neurons have nuclear Hnf6 (K). (L–N) Serotonergic neurons of the animal plate are a subset of ciliary band-associated neurons in the early pluteus larva. Bars = 20 µm.