Ultrastructural organization of microtubules in the outer segment of haltere campaniform receptors. (A) Cartoon schematic of the sensory neuron in haltere receptors. BB, basal body. (B) The localizations of NompC-GFP (MO), Mks1-GFP (transition zone [TZ]), and GFP-Cnn1 (BB) in haltere receptors (top view). Upper: nompC-gfp-KI. Middle: Mks1-gfp. Lower: uas-gfp-cnn1/+; +/+; dcx-emap-gal4/+. Scale bar, 5 µm. (C–F) Cross-sectional views of the MO (C), neck (D), TB (E), and cilium (F). (G) Lateral view of the cilium. Black arrowhead, a doublet. (H) Lateral view of the mother centriole (MC), daughter centriole (DC), and cilium. Scale bars (C–H), 250 nm. C–H are ET slice images. (I) Reconstructed model of microtubules in the outer segment. Each microtubule was shown as a rod. White, microtubule in the outer segment. Red (tubule-A) and green (tubule-B), doublet. Yellow, microtubule in the inner segment. Scale bar, 1 µm. Also see Video 1.