Brain and ventral nerve cord of the tentacular and vestimental regions in <i>L. satsuma</i>.

<p><b>A–C:</b> Z-projection images of anti-SYNORF1 and anti-serotonin immunoreactivities showing Anti-SYNORF1 positive neuropils and serotonergic neurons of the brain and the ventral nerve cord. <b>D–F:</b> Z-projection images of anti-SYNORF1 and anti-serotonin immunoreactivities at the anterior end of the central nervous system. A pair of prominent neuropils is connected through the anterior (arrows) and posterior (arrowheads) connectives. <b>G–I:</b> Three-dimensional reconstructions of the central nervous system. Ventrolateral view (G) and dorsolateral view (H) views show that anti-SYNORF1 positive neuropils in the brain are thickened dorsally. Serotonergic neurons are located on the ventral and lateral sides of the anti-SYNORF1 positive neuropils. <b>I:</b> Dorsal view of the brain: anterior is up. The anterior (arrows) and posterior (arrowheads) anti-SYNORF1 positive signals connect a pair of neuropils. <b>J, K:</b> Expression patterns of <i>elav</i> (J) and <i>syt</i> (K) showing the distribution of neural cell bodies. <b>L:</b> Section through the posterior end of the brain neuropils. Dorsal is up. Double stain of <i>syt</i> (brown) and <i>elav</i> (yellow) shows the overlapped expression patterns of these neuron marker genes. The neuropils are encapsulated by neurons. <b>M−O:</b> Cross sections of brain. Positions are shown in <b>D</b>. The cell bodies cover the neuropils. Scale bars: 100 µm. br, brain; vcf, ventral ciliated field.