Fig. 12

Late metamorphosis and early juvenile development in Schizocardium californicum. Larvae are labeled with four markers: phalloidin (green), anti-acetylated tubulin (red) and anti-serotonin (yellow) antibodies, and DAPI (blue) unless otherwise indicated. a-e 24 h after onset of metamorphosis. Anterior to the top. b Serotonin labeling only. Inset shows a close-up on the larval apical organ, still visible. c Phalloidin labeling only, showing longitudinal muscles in the trunk. d Close-up of the anterior proboscis, serotonin and DAPI labeling only. Neurons of the larval apical organ are still visible, but become less distinct from the broadly distributed neurons of the juvenile proboscis as time progresses. e Serotonin labeling only. Insets show optical slices through the anterior tip and ventral side of the proboscis epidermis. f Early juvenile, 48 h after onset of metamorphosis. Surface optical slices are excluded from the stack, showing muscles inside the proboscis and trunk. g Close-up view of the trunk epidermis, showing basiepidermal serotonergic nerve net and muscle fibers underlying the ciliated epithelium. h Juvenile, 15 days post-metamorphosis. ao, apical organ; c, collar; dn, dorsal neurite bundle; dv, dorsal view; gb, gill bars; gp, gill pore; lv, lateral view; m, mouth; pm, proboscis muscles; pr, proboscis; t, telotroch; tm, longitudinal trunk muscles; tr, trunk; vn, ventral neurite bundle. Scale bars: 500 μm (a-c, e-f, h), 100 μm (d), 200 μm (g)