Fig. 4

Volume rendering of the serotonin-lir nervous system of the ctenostome Paludicella articulata. a Overview of the polypide with the serotonin-lir nervous sytem (yellow) and the musculature (glow/red). b Detail of the serotonin-lir nervous system showing the concentration at the lophophoral base, the tentacle sheath nerves and the latero-visceral nerves innervating the foregut. c Parts of the serotonin-lir nervous system in a dissected zooid of P. articulata showing main parts of the serotonin-lir cystid innervation. d Close-up of the serotonin-lir concentration at the lophophoral base and the serotonin-lir anal tube. e Optical section through the esophagus showing the serotonin-lir perikarya within the lining of the esophagus. f Close-up of a parietal nerve innervating the parietal musculature. Abbreviations: a - anus ca – cardia, cae – caecum, cg – cerebral ganglion, con – circum-oral nerve ring, el – esophagus lumen, es – esophagus, lb – lophophore base, lvn – latero-visceral nerve, np – nucleus of the peritoneal lining, pm – parietal muscle, pn – parietal nerve, pvn – parieto-vaginal nerve, py - pylorus, re – rectum, rm – retractor muscles, sat – serotonin-lir anal tube, sc – serotonincilia, sp – serotonin-lir perikarya, spy – serotonin-lir pyloric ring, tsn – tentacle sheath nerve, vwi – vestibular wall innervation