Fig. 16

Details of the stomatogastric nervous system in Syllidae. a: Syllis tyrrhena. Maximum intensity z-projection of α-tubulin-lir, dorsal planes, anterior segments. Green arrow: stomatogastric neurite bundles turning towards the anterior end of the pharynx. Yellow arrow: stomatogastric neurite bundles turning posteriorly underneath the muscular layer of the parynx. Yellow arrowheads: ciliary patches on the first three chaetigers. b: S. tyrrhena. Colour coded z-projection of α-tubulin-lir. Detail of neurite bundles entering pharynx. c:Sphaerosyllis taylori. Colour coded z-projection of α-tubulin-lir. Detail of the pharynx and pharyngeal gland. The pharyngeal glands show a strong α-tubulin-lir signal in this species. d: Syllis garciai. Detail of everted pharynx. The pharyngeal papillae are covered in ciliary receptor cells, innervated by numerous neurite bundles (turquoise arrowhead) branching off of the stomatogastric neurite bundles. e: Plakosyllis brevipes. Maximum intensity z-projection of α-tubulin-lir (grey), serotonin-lir (orange) and cell nuclei (magenta) of the dissected pharynx. Autofluorescence shows four plates inside the proventricle. White arrowhead: neurite bundles traversing the proventricle. f:S. tyrrhena. Semi-thin cross section through the pharyngeal glands and layers of pharyngeal sheath. g, h:Sph. taylori. Volume rendering of f-actin (glow) and α-tubulin-lir of the pharynx. The pharyngeal innervation and pharyngeal glands were segmented, other neurites are omitted. g: Cross section shortly before the first segmental ring neurite bundle. Black arrowheads: three layers of neurite bundles are visible. h: Cross section shortly before second pharyngeal ring neurite bundle. Black arrowhead: one layer of stomatogastric neurite bundles is visible. Pink arrowhead: signal inside the pharyngeal glands. i: S. tyrrhena. Maximum intensity z-projection of α-tubulin-lir. Detail of the ventricle and its four thick neurite bundles. j: S. tyrrhena. Maximum-intensity z-projection of serotonin-lir. Intestine just behind the ventricle. Scale bars: A-C = 100 μm, D = 50 μm, E = 100 μm, F-H = 50 μm, I, G = 100 μm. Abbreviations: br – brain; bv – blood vessel; cno – cilia of support cells of nuchal organ; cp – cuticularised layer of pharynx; cpl – cuticularised plates inside proventricle of P. brevipes; cr – ciliary receptor; dcb – dorsal ciliary band; dlm – dorsal longitudinal muscles; ep – epidermal layer of pharyx; glp – pharyngeal glands; lln – lateral longitudinal neurite bundle; mlp – muscular layer of pharynx; ppa – pharyngeal papilla; ppl – parapodial lobe; ph – pharynx; pin – nervous plexus of the intestine; pm – parapodial muscle; pxm – muscles of the pharynx; r1 – stomatogastric ring neurite bundle 1; r2 – stomatogastric ring neurite bundle 2; stgn1–5 – stomatogastric neurite bundles 1–5; th – tooth; venn – neurite bundles innervating ventricle; ven – ventricle; vlm – ventral longitudinal muscles; vnc – ventral nerve cord. Segmental neurite bundles in yellow: I – segmental neurite bundle I; IIr – ring commissure of segmental neurite bundle II; III – segmental neurite bundle III