Fig. 4

Morphology of the tornaria larva of Schizocardium californicum at 5 dpf and 10 dpf. a-c, p-r Light DIC micrographs of live specimens. Optical sections through the middle of the embryo (a-p) or surface views (b-c, q-r). d-o, s-y Maximum intensity projections of confocal stacks. Larvae are labeled with four markers: phalloidin (green), anti-acetylated tubulin (red) and anti-serotonin (yellow) antibodies, and DAPI (blue) unless otherwise indicated. All panels are anterior to the top, and lateral views are ventral to the left. a-o Tornaria larva at 5 dpf. f, m Close-up views of the circular pharyngeal muscles and apical strand. i-j, o Close-up views of the apical organ and dorsally projecting neurites. p-y Tornaria larva at 10 dpf. w-y Close-up views of the apical organ and dorsal nerve tract. af, anal field; am, anchoring muscles; ao, apical organ; as, apical strand; av, anterior view; dc, dorsal cluster of the apical organ; dn, dorsal nerve tract; dv, dorsal view; e, eyespots; i, intestine; lv, lateral view; m, mouth; mc, mesenchymal cell; n, neuropil; nt, neurotroch; of, oral field; p, protocoel; ph, pharynx; pm, pharyngeal muscles; pof, post-oral field; post, postoral loop of the circumoral ciliary band; pp, protocoel pore (hydropore); pre, preoral loop of the circumoral ciliary band; prf, preoral field; s, stomach; t, telotroch; vc, ventral cluster of the apical organ; vv, ventral view. Scale bars: 100 μm (a-e, g-l, p-v), 50 μm (f, m, o, w-y)