Fig. 9

Details of innervation of tentacle crown and oral area in Owenia borealis. CLSM data: Z-projections after immunostaining against acetylated alpha-tubulin (grey) and serotonin (green). A The aboral side of tentacle base: several short thick nerves (arrowheads) extend from the anterior nerve center and give rise to the oral neurite bundles of tentacles. B Serotonin-lir perikarya and neurites in the epithelium of tentacle. C Central portion of the head: circumoral nerve ring is visible. D Central portion the head: serotonin-lir neurites are visible in the circumoral nerve ring. The epithelium of pharynx contains numerous serotonin-lir cells. E A portion of the head viewed from the ventral side. There are anterior and posterior portions of the anterior nerve center. Right ventrolateral root of the circumoral nerve ring and ventral commissure are visible. F Right portion of the head viewed from the ventral side. Abbreviations: aac – anterior portion of the outer ring of the anterior nerve center; anc – outer ring of the anterior nerve center; atn – aboral tentacle nerves; com – ventral commissure; cor – inner (=circumoral) ring of the anterior nerve center; es – esophagus; lmc – lateral medullary cord; og – oral groove; otn – oral tentacle nerves; pac – posterior portion of the outer ring of the anterior nerve center; ph – pharynx; rcor – root of circumoral nerve ring; sp. – serotonin-lir perikarya; stn – serotonin-lir neurites of tentacles; t – tentacle; vmc – ventral medullary cord