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Fig. 7 | BMC Biology

Fig. 7

From: The visual pathway in sea spiders (Pycnogonida) displays a simple serial layout with similarities to the median eye pathway in horseshoe crabs

Fig. 7

Distribution of neuroactive substances in protocerebral structures of E. spinosa. A 3D-reconstructed volume rendering of the brain, μCT scan, lateral view. Stippled brackets indicate the positions of the extended sections shown in BI. BI Oblique sections of immunolabeled whole-mount brains shown either in MIP (B,DI) or in blend mode (C). Solid oval (B,C,E,F) demarcates an antero-dorsal cluster of serotonin-ir neuronal somata. B Tubulin (TUB, magenta) and serotonin (5HT, green) with nuclear counterstain (NUC, gray). C Synapsin (SYN, gray) and serotonin (green). Note absence of serotonin signal in the visual and antero-median neuropils and in the upper arcuate body layer. DF Tyrosine hydroxylase (TH, magenta, only D,E) and serotonin (green, only E,F). Arrowheads and arrows point at the somata of type 1 and type 2 TH-ir interneurons, respectively. Note largely complementary distribution of TH-ir and serotonin-ir synaptic varicosities in the upper and lower arcuate body layers. G Orcokinin (ORCO). Note a few orcokinin-ir projections through the antero-median tract toward the lower arcuate body layer. Arrows point to somata of orcokinin-ir interneurons projecting into the antero-median neuropil. H Proctolin (PROC). Note proctolin-ir synaptic varicosities in the antero-median neuropil and sub-visual domain, but lack of signal in the arcuate body. I Allatostatin (AST). Note dense allatostatin-ir synaptic network in the antero-median neuropil and the lower arcuate body layer. Abbreviations: ABL – lower arcuate body layer; ABU – upper arcuate body layer; AMN – antero-median neuropil; AMT – antero-median tract; BR – brain; DPL – dorso-posterior lobe; LO – lateral sense organ; LONV – lateral sense organ nerve; LT – lateral thickening; ONV – optic nerve; PNV – proboscis nerve; SVD – sub-visual domain; VN – visual neuropil

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