Fig. 7
From: The visual system of harvestmen (Opiliones, Arachnida, Chelicerata) – a re-examination
Transmission electron microscopy of first and second visual neuropil of Platybunus pinetorum (a, c, and f sagittal sections; b, d, e, g, and H transversal sections; dorsal is up). a, b showing arrangement of retinula axons (bright cells with high electron density) and dendrites of visual second order neurons (dark cells with low electron density) in first visual neuropil. Bars 5 μm and 10 μm, respectively. c detail of first visual neuropil with synapses (arrowheads) between retinula axons and visual second order neurons. Bar 2 μm. d, e transition area between first and second visual neuropil with neuropil border; note first and second neuropil with different anatomy and neuron gestalten; note several retinula axons traverse neuropil border (arrows). Bars 10 μm. f, g and h detail of transition area between first and second visual neuropil with various retinula axons traversing neuropil border (arrows). Bars 10 μm, 5 μm, and 5 μm, respectively. M, median eye visual neuropil; NB, neuropil border