Fig. 11

Details of innervation of the lophophore and the tentacles in Amathia gracilis. 3D-reconstructions (a, c–e) and 3D-reconstructions combined with volume renderings based on confocal image stacks (b). The apical is on the top in all micrographs except for E, which is viewed from the top of the lophophore. a Main nerve tracts projecting from the cerebral ganglion. Anal view. Three commissures of the cerebral ganglion are indicated by asterisks. b Localization of the circum-pharyngeal nerve plexus and visceral nerve tracts. Three commissures of the cerebral ganglion are indicated by asterisks. c Tentacular nerves projecting from the circum-oral nerve ring and lophophoral dorso-lateral nerves. d Innervation of the tentacles closest to the mouth: the intertentacular site closest to the mouth has no connection to the abfrontal tentacle nerve. View from the anal side. e 3D-reconstruction of the serotonin-like immunoreactive nerve system of the lophophore. Abbreviations: af - abfrontal tentacle nerve; cg - cerebral ganglion; con - circum-oral nerve ring; cpp - circum-pharyngeal nerve plexus; cpr - circum-pharyngeal nerve ring; its - intertentacular site; ldl - lophophoral dorso-lateral nerve; lf - latero-frontal tentacle nerve; mf - medio-frontal tentacle nerve; mln - medio-lateral visceral nerve; mvn - medial visceral nerve; oits - intertentacular site closest to the mouth; on - outer nerve ring; sn - serotonin-like immunoreactive intertentacular neurites; spk - serotonin-like immunoreactive perikarya between tentacles; tsn - tentacle sheath nerve; tsr - tentacle sheath nerve ring