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Fig. 8 | BMC Biology

Fig. 8

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

Fig. 8

Protocerebral sense organs and their connection to the brain in Nymphonidae. Nymphon gracile (A–C), N. stroemi (D), and N. cf. multituberculatum (E). A 3D-reconstructed volume rendering of protocerebral sense organs and their connection to the brain, μCT scan, lateral view. The arrow points at the lateral sense organ nerve. Stippled brackets indicate the positions of the sections shown in D and E. B–E Extended optical sections of immunolabeled samples (MIP). B,B’ Tubulin (TUB, green), para-sagittal section. The tubulin-labeled lateral sense organ and its nerve (arrow) have been segmented and highlighted in magenta. The asterisk marks a tubulin-rich spherical body in the anterior soma cortex. B Tubulin with nuclear counterstain and autofluorescence (AF + NUC, gray). B’ Tubulin with synapsin (SYN, gray), lower image shows only the segmented lateral sense organ with its nerve, which passes through the lateral thickening and diverges from the optic nerve toward the antero-median neuropil (yellow arrowhead). C Tubulin (magenta) and orcokinin (ORCO, green) with nuclear counterstain and autofluorescence (gray, only upper image). Arrows mark the lateral sense organ nerve, and arrowheads indicate orcokinin-ir cell bodies in the lateral sense organ. D Tubulin (green) and synapsin (magenta), horizontal section. Note bipartition of the axon bundles targeting the visual neuropil (arrowheads) and the separate course of less intensely stained neurites toward the antero-median neuropil (red arrow). E Orcokinin, cross section. Single orcokinin-ir neurites pass through the lateral thickening and project toward the antero-median neuropil (yellow arrowheads). Note virtual lack of signal in the poorly defined antero-median tract. Abbreviations: AE – anterior eye; AMN – antero-median neuropil; AMT – antero-median tract; BR – brain; CHNV – cheliphore nerve; LO – lateral sense organ; LT – lateral thickening; ONV – optic nerve; PE – posterior eye; PNV – proboscis nerve; VN – visual neuropil

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