Structural plasticity of an immunochemically identified set of honeybee olfactory interneurones

Using a monoclonal antibody (FB 45) raised by Dr. A. Hofbauer (Würzburg) against Drosophila brain we investigated the development and plasticity of immunoreactive cells belonging to the median and lateral antennoglomerular tracts (AGTS) in the honeybee brain. In early stages of pupal development presumed AGT immunoreactivity was detected in the diffuse central neuropil of the antennal lobe as well as in the glomeruli, which differentiate at 40% pupal development. The lateral protocerebral lobe--one target area of the AGTs--is labelled throughout pupal life whereas labelling in the calyces is first restricted to the basal ring region. Although the lips of the calyces develop in middle-aged pupae, they do not show immunoreactivity until the last day of metamorphosis. Unilateral ablation performed on pupae of different stages resulted in size reduction of the antennal lobe and fusion of glomeruli. The number of labelled somata and glomeruli in the antennal lobe were reduced on the treated side. These effects were more prominent when ablation was performed in young pupae. No differences in staining intensity at the light microscopic level were found in the calyces. Therefore a pre-embedding immunohistological approach was developed to detect AGT profiles in the mushroom body at the electron microscopic level.