Fig. 5

Sphaerosyllis taylori. Innervation of prostomium and anterior segments. a-c: Single optical frontal sections of α-tubulin-lir (grey), serotonin-lir (and autofluorescence of tissue) (orange) and cell nuclei (magenta) of a single individual. a: Dorsal and nuchal lobes. b: Neuropil of the brain. Fibres (black arrow) of the nuchal neurite bundle enter the posterior inferior cluster of somata as do fibres (white arrow) of the dorsal root of the circumoesophageal connective. Dorsal fibres of the vrcc form an anterior commissure. The yellow arrow indicates the loop where the stomatogastric neurite bundles enter the pharyngeal epithelium. c: Ventral part of the brain showing posterior inferior cluster of somata (pink dotted line). d: Maximum intensity z-projection of dorsal part of brain showing where the circumoesophageal connectives enter the brain. e: Maximum intensity z-projection of ventral part of brain. The black arrowhead indicates the neurite bundle forming ventral, lateral and dorsal longitudinal neurite bundles. f: Maximum intensity z-projection of serotonin-lir of dorsal planes. g: Resliced cross section through the brain, combined α-tubulin-lir, serotonin-lir and cell nuclei staining. The dcvr reaches dorsally, forming a median (and an anterior) dorsal commissure. h: Resliced cross section showing the position of the dorsal and nuchal lobes, combined α-tubulin-lir, serotonin-lir and cell nuclei staining. Scale bars = 50 μm. Abbreviations: acvr – anterior dorsal commissure of vrcc; ae – anterior eye; br – brain; cc – circumoesophageal connective; cno – cilia of support cells of nuchal organ; dcvr – dorsal commissure of vrcc; dl – dorsal lobe; drcc – dorsal root of circumoesophageal connective; la – lateral antenna; lfs – laterfrontal sense organ; mcvr – median dorsal commissure of vrcc; nl – nuchal lobe; nn – nuchal neurite bundle; pic – posterior inferior cluster of somata; pk – serotonin-lir perikarya; pn 1 – main palp neurite bundle; pn 2 – palp neurite bundle from drcc; pn 3 – palp neurite bundle from vrcc; pon – posterior neurite bundle of the brain; ppa – pharyngeal papilla; sn 1 and 2 – segmental neurite bundles innervating posterior edge of tentacular segment; sp. – sensory papilla; srn – segmental ring neurite bundle; stgn 1–5 – stomatogastric neurite bundles 1–5; tc – tentacular cirrus; tcn – neurite bundle innervating tentacular cirrus; tln – tubulin-lir fibres from nuchal organ entering nuchal lobe; th – tooth; vln – ventral longitudinal neurite bundle