Three-dimensional reconstruction of the antennal lobe in Drosophila melanogaster

We present the first three-dimensional map of the antennal lobe of Drosophi la melanogaster, based on confocal microscopic analysis of glomeruli staine d with the neuropil-specific monoclonal antibody nc82. The analysis of conf ocal stacks allowed us to identify glomeruli according to the criteria shap e, size, position, and intensity of antibody labeling. Forty glomeruli were labeled by nc82, eight of which have not been described before. Three glom eruli previously shown exclusively by backfills were not discernible in nc8 2 stainings. We distinguish three classes of glomeruli: (1) "landmark" glom eruli that are constant in all four criteria mentioned above, (2) less well -demarcated glomeruli that deviate in a single criterion, and (3) poorly de fined glomeruli that vary in more than one criterion. All class 2 and 3 glo meruli can be identified by comparison with landmark neighbors. To further aid identification, our model assigns glomeruli to five arrays, each of whi ch is defined by a prominent landmark glomerulus. Six glomeruli consist of distinct, but contiguous structural units, termed "compartments." Glomerula r variability observed occasionally between males and females is in the sam e range as between individuals of the same sex, suggesting the lack of a si gnificant sexual dimorphism in the glomerular pattern. We compare the new m odel with a previous map and address its potential for mapping activity and expression patterns. An important goal of this work was to create three-di mensional reference models of the antennal lobe, which are accessible on-li ne. (C) 1999 Wiley-Liss, Inc.