Fig. 1. Confocal micrograph of the honeybee antennal lobe with labelled projection neurons. Injections of dextran-coupled rhodamine into the mushroom bodies stained projection neurons (PN); their somata are clustered around the antennal lobe. In this specimen only the median cluster was labelled, but in other preparations the other clusters around the antennal lobe were also labelled. The roots of the antennocerebralis tracts (ACT) are also stained (arrows). Within the protocerebrum the somata of mushroom body feedback neurons within a lateral cluster are densely stained (asterisk), because they innervate all calycal regions. Frontal view of a whole-mount preparation; lateral (l) and dorsal (d) directions are indicated. Scale bar, 50 µm.