Fig. 4.

Colocalization of PDF (blue) and orcokinin (red) immunoreactivity in the central brain of the cockroach (a–c), plus neurobiotin (green) backfills from the cut optic lobe stump (d). Confocal laser scan images were obtained from vibratome sections of the accessory medulla (AMe; a, c), posterior PDFMe (b), and superior lateral protocerebrum (d). Left Overlay images. a, b Maximum projections from stacks of optical sections. c, d Single optical sections. a _1-4 Small (small open arrows) and medium-sized (large open arrows) anterior PDFMe show colocalized PDF and orcokinin immunoreactivity, whereas large PDFMe (large filled arrows) are only PDF-ir. b _1-3 Of the posterior PDFMe neurons near the lobula valley tract (LoVT), neither the small neurons (open triangles), nor the large neurons (filled triangles) show additional orcokinin immunoreactivity. c _1-3 Most orcokinin-ir fibers in the accessory medulla are not found in the anterior shell neuropil but in the distal shell neuropil between AMe and medulla (arrowhead). Colocalization was not observed in PDF-ir fiber terminals in the AMe. d _1-4 No PDF/orcokinin-ir colocalization is observed in the region of the dorsal superior lateral protocerebrum (dSLP), although orcokinin-ir fibers are abundant. Occasional orcokinin-ir fibers of unknown origin are labeled by neurobiotin backfill (filled arrowheads). Bars 50 μm