Fig. 8. Babo regulates extension and targeting of AL and OL axons independently of Smads. (A) Schematic of the adult Drosophila brain. Shown from the left hemisphere, antennal lobe (AL) contralateral projection neurons elaborate dendrites (green) ipsilaterally to one AL, but project axons contralaterally to the opposite AL. The blue boxed region indicates the location of all represented AL images. Also, from the left hemisphere, optic lobe (OL) contralateral projection neurons elaborate dendrites (green) ipsilaterally to one OL, but project axons contralaterally to the opposite OL. The red boxed region indicates the orientation of all represented OL axons. Green circles indicate cell bodies. (B-I) Wild-type (B,F), babo⁵² (C,G), Smad2¹ (D,H) and Med¹³ (E,I) AL (B-E) and OL (F-I) contralateral projecting neurons. White arrows indicate a wild-type number of axons that reach the target zone. Open white arrows indicate axon extension defects. Blue arrowheads indicate wild-type axon termination zones. Open blue arrowheads indicate targeting defects (`gaps'). Scale bar: 20 µm. See also Fig. S5 in the supplementary material. (J) Quantification of these OL (grey bars) and AL (black bars) phenotypes. n, number of clones analysed.