16% of mushroom bodies lack dorsal projections in learobo2-1/learobo2-5 animals, and 32% have a partial median projection. In addition, the diameter of the peduncle is larger than in wild-type animals.
34% of mushroom bodies lack dorsal projections in learobo2-4/learobo2-1 animals, and 18% have a partial median projection. The median lobes are positioned more posteriorly than in wild type. In addition, the the diameter of peduncle is larger than in wild-type animals.
learobo2-1/learobo2-1 DM2 glomerulus innervating neurons, produced by mitotic recombination in a learobo2-1/+ background, fail to cross over to the contralateral lobe through the antennal commissure. Instead they terminate at the midline forming small "glomerular-like" structures. Targeting of these neurons to antennal glomerulus DM2 occurs normally, although in many cases the glomeruli appear less intensely innervated (13/16).
The lateral Fas2-expressing fascicle often merges with the intermediate fascicle in learobo2-1/learobo2-4 mutant embryos. Midline crossing defects also occur. 7.9% of embryos show fusion between the medial and intermediate fascicles, 17.1% show fusion between the lateral and and intermediate fascicles and 13.4% show breaks in the lateral fascicle.