Figure 2

The lobula plate is present only in the lower optic lobe in the adult whirligig beetle. A-H: Eight consecutive reduced silver-stained frontal brain sections taken from the anterior to posterior optic lobe, and the schematic drawings pertaining to each level, demonstrate the position of the lobula plate (LOP, magenta), which first appears just beneath the lower part of the lobula (B-D) and is then revealed to be restricted to the lower half of the optic lobe (E-H). The upper lobe of the lobula is fragmented by small parallel bundles of axons that project directly from the upper medulla towards the medial protocerebrum (B-D, arrows). uLA and lLA, upper and lower lamina; uME and lME, upper and lower medulla; LO, lobula. All panels are of the same magnification (bar in A = 200 μm).