Fig. 8

Schemes of the lophophore and of the tentacle sheath innervation in Amathia gracilis. a Organization of the serotonin-like immunoreactive nervous system of the lophophore, viewed from the left. b Top view of the nerve elements after staining for tyrosinated α-tubulin. c The main nerve tracts of the lophophore and the tentacle sheath. Lateral view. Only the bases of the front tentacles are shown. d Combination of the serotonin-like and the α-tubulin-like immunoreactive nerve elements of the lophophore. Top view. Abbreviations: af - abfrontal tentacle nerve; cg - cerebral ganglion; co - collar; con - circum-oral nerve ring; cpr - circum-pharyngeal nerve ring; cpp - circum-pharyngeal nerve plexus; cgn - ventro-lateral nerves of the cerebral ganglion; hpk - perikaryon of the cerebral ganglion ventro-lateral nerve; its - intertentacular site; ldl - lophophoral dorso-lateral nerve; lf - latero-frontal tentacle nerve; lph - lophophore; m - mouth; 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; sc - serotonincilia; sn - serotonin-like immunoreactive intertentacular neurites; spk - serotonin-like immunoreactive perikarya between tentacles; t - tentacle; tsh - tentacle sheath; tsn - tentacle sheath nerve; tsr - tentacle sheath nerve ring