Fig. 11.

Neurogenesis in female Dinophilus gyrociliatus (a-e) and D. taeniatus (f-m) as revealed by serotonin-LIR. Serotonin-like immunoreactive elements shown as black structures on white background, animals are oriented with the anterior end up. Stages are indicated by silhouettes next to the figure capture, and the assignment to the respective stage next to them. The first signs of difference between the two species D. gyrociliatus and D. taeniatus are emphasized by a yellow dashed-lined frame around the picture. a, b embryonic development: a ventral view of the first indication of the serotonin-like immunoreactive nervous system in early embryos of D. gyrociliatus with perikarya forming along the ventral nervous system, b ventral view of a detail of the ventral nervous system with governing perikarya in ventral ciliary field stage, c ventral view of the head in a juvenile female, d ventral view of a detail of the nervous system in the anterior trunk segments in a hatching female, e ventral view of the serotonergic nervous system in an adult female, f-j embryonic development: f ventral view of an embryo at 1 ciliary band stage with first immunoreactive perikarya being located near the first commissure, g ventral view of an embryo at ventral ciliary field stage with four perikarya being detected in the head region, h ventral view of a late embryo, i detail of h) of the ventral nervous system, j ventral view of a juvenile specimen, k dorsal view of a juvenile with four perikarya dorsal to the neuropil, l ventral view of an adult specimen displaying a regular ladder-like organization of the ventral nervous system, m lateral view of an adult specimen. Abbreviations: acom – anterior commissure, cmvn – circumesophageal commissure forming the medioventral nerve, com1-5 – commissure 1–5, cvln – circumesophageal commissure forming the ventrolateral nerve cord, dpn – dorsal peripheral nerves, lpn – longitudinal peripheral nerve, mcom – median commissure, mo – mouth opening, mvn – medioventral nerve, nacb – lateral nerve anterior to the ciliary band, nar – nerves innervating the anterior rim, ncb – nerve of the ciliary band, nis – intersegmental lateral nerve, npcb – lateral nerve posterior to the ciliary band, pcom – posterior commissure, pmvn – paramedioventral nerve, snp – serotonin-LIR portion of the neuropil, sp – serotonin-LIR perikaryon, spbr – serotonin-LIR perikaryon of the brain, spl – serotonin-LIR plexus, spst – serotonin-LIR perikaryon of the stomatogastric nerve ring, stnr - stomatogastric nerve ring