α-RDL immunoreactivity in the visual system of Calliphora. A Overview of α-RDL-immunoreactivity in a horizontal section. Besides immunopositive staining (dark labeling) in the neuropilar regions of the medulla, lobula and lobula plate, there is also significant immunoreactivity present in somata located distal to the medulla, inside the inner chiasma and in the soma layers anterior and posterior to the medulla and lobula complex (asterisks). B Control in an adjacent section incubated with preabsorbed primary antibody. C High magnification view of the medulla. The highest level of immunoreactivity is found in layer L1. There are also 2 more weakly labeled strata in the outer medulla (L3, proximal L1). The inner medulla also shows some α-RDL immunoreactivity. Somata with α-RDL immunoreactivity in the outer chiasma are indicated by arrows. D Control in an adjacent section with preabsorbed primary antibody. E High magnification view of lobula and lobula plate. The posterior lobula shows a similar pattern with two layers in its α-RDL immunoreactivity, as was also observed in the α-ARD labeling (see figure 2B). α-RDL immunoreactivity in the distal lobula plate also resembles α-ARD immunoreactivity with layered labeling. Dark stripes are artifactual labeling of trachea. Scale bar in A, B: 62.5 μm; in C, D 25 μm; E 16 μm.