Fig. 2

Histological sections of the head. a Frontal section of the head with posterior part of the brain. The brain is surrounded by numerous lipid droplets (brownish spherules). The dorsal-most part of the brain is innervated by paired small nerves (double-arrow). The optical nerve forms a chiasm (red arrow). b Magnification of the chiasm (red arrow) of the optical nerve of the left brain hemisphere, frontal view. c Magnification of the first and second visual neuropil of the right brain hemisphere displaying a chambered appearance of the lamina, frontal view. Numerous terminations within each chamber are visible. Somata of cluster 1 appear darker and smaller. d Frontal section of the anterior part of the brain. A small section of the antenna 1 nerve projects to the deutocerebral chemosensory lobe (red arrows). The medial foramen is discernable (double-arrow). Insets (bottom left corner in A and D) show position and orientation of depicted sections in the brain. Abbreviations: a1nv antenna 1 nerve, ann antenna 2 neuropil, ao anterior aorta, ba brain artery, dcl deutocerebral chemosensory lobe, ec esophageal connective, es esophagus, hn/tm hemiellipsoid body/ terminal medulla complex, la lamina, lo lobula, maf a myoarterial formation a, me medulla, om ommatidia, onv optical nerve, pc protocerebrum, re retina, [numbers] somata cluster. Scale bars: (a) 100 μm, (b-d) 50 μm