Fig. 8

Immunoreactivity against serotonin (a-c), FMRFamide (d-f), FVRIamide (g-i), and MIP (j, k) in the nervous system of the copulatory organ in adult males of Trilobodrilus axi (a, d, g, j), Dinophilus vorticoides (b, e, h), and D. gyrociliatus (c, f, i, k). Maximum intensity projections of CLSM-images. a, b, d, e, g, h, j) Ventral view, ventral part of z-stack, c, f, i, k) posterior view, transverse 3D crop through the copulatory organ. For the large D. vorticoides (b, e, h) only a small subsample of the entire stack has been compiled into a 2D image, omitting some of the traits described in Figs. 4 and 5. Asterisks in (a) mark artefacts (a fold in the animal led to a stronger accumulation of serotonin-IR) and no real immunoreactivity against serotonin of neural elements. Abbreviations: com5, 6 – commissure of the fifth/sixth body segment, cpfm – circumpenial fibre mass, dpc – dorsal penial commissure, gd – gland ducts, gp – gonopore, mvn – medioventral nerve, nsv –nerves of the seminal vesicles, n15 – neurite extending from dorsoposterior sensory neuron 15 (nomenclature based on Windoffer & Westheide 1988a, b), osv – opening of the seminal vesicles to the testes, pco – penis cone opening, pg – penial gamglion, pmn – paramedian nerve, pvc – posterior ventral ciliation, sv – seminal vesicle, test – test, vlnc – ventrolateral nerve cord, vpc – ventral penial commissure