H-neuron projections are initially symmetrical (28 h APF) and resolve into an asymmetrical circuit (48 h APF) during an ~20 h-long process. Confocal images of representative H-neurons (magenta) stained with anti-Fas2 antibody (cyan) during pupal stages. ABs (white dotted lines) and noduli (white arrows) are shown. Projections of H-neurons in the different categories are as follows (from left to right): “AB nucleation”, vertical projection in fan-shaped body (FB), in noduli and symmetrical in left and right AB primordia; “Bilateral fused”, symmetrical projection in fused left and right ABs; “bilateral”, symmetrical projection in separated left and right ABs; “Bilateral with right bias”, asymmetrical projection in separated left and right AB (right AB volume >3x left AB volume); and “Right”, asymmetrical projection in right AB exclusively. Scale bars, 10 m.
