Fig. 5

Architecture of Parhyale optic lobes. a Whole-mount stage 27 embryonic brain stained with an antibody for acetylated tubulin. The optic nerve (ONv) connects the retina (Re) to the first optic neuropil (1). A chiasm (Ch) is present between the first (1) and the second (2) neuropils. A third neuropil (3) is also distinguishable. Scale bar, 10 μm. b Section of an adult brain stained with acetylated tubulin antibody. Higher order neurons (arrowheads) connect the second optic neuropil (2) and the central brain (CB). Scale bar, 10 μm. c Adult retina stained with acetylated tubulin. Photoreceptor axons converge at the back of the retina forming the optic nerve. Scale bar, 20 μm. d Section of an adult brain stained with DAPI and with an antibody for acetylated tubulin. Photoreceptor axons emerge from the retina (Re) and converge ventrally forming the optic nerve which connects to the first neuropil (1). The second (2) and third (3) neuropils are also visible. Scale bar, 20 μm. e, e′ Detailed view of the optic nerve (same specimen as in panel d) imaged at different tissue depths, suggesting a potential chiasm. Axons emerging from the retina connect to the anterior/frontal part of the first optic neuropil (arrowheads in e). Focusing 10 μm deeper within the optic nerve reveals axons connecting to the posterior part of the first neuropil (arrowheads in e′). Scale bar, 10 μm. f Detailed view of the connections between optic neuropils 1, 2 and 3 (same specimen as in panel d), forming a chiasm (Ch) between neuropils 1 and 2. Scale bar, 10 μm. g Horizontal semi-thin section through a Parhyale adult brain, stained with toluidine blue, showing part of the retina (Re) and the three optic neuropils. Scale bar, 20 μm. h 3D reconstruction of the retina and optic lobe of Parhyale based on whole-mount adult brain stained with an antibody for acetylated tubulin. The first neuropil (1) is located anteriorly and ventrally relative to the other neuropils. i, i′, i″ Whole-mount adult Parhyale brain stained with DAPI and with antibodies for tyrosinated tubulin and synapsin. The three neuropils can be distinguished by synapsin immunostaining (labelled 1, 2 and 3). Within the first neuropil, synapsin staining is strongest in the inner part of the neuropil (i′). The chiasm between the first and second neuropil is visible (i″). Scale bars, 20 μm