Ultrastructural organization of microtubules in the outer segment of leg campaniform receptors. (A) Cartoon schematic of the sensory neuron in leg receptors. (B) The localizations of NompC-GFP (MO), Mks1-GFP (transition zone [TZ]), and GFP-Cnn1 (basal body [BB]) in leg receptors (lateral view). Upper: nompC-gfp-KI; dcx-emap-gal4, uas-cd4-tdTom/+. Middle: +/Mks1-gfp; +/dcx-emap-gal4, uas-cd4-tdTom. Lower: uas-gfp-cnn1/+; +/+; dcx-emap-gal4, uas-cd4-tdTom/+. Scale bar, 5 µm. (C) Lateral view (ET slice image) of the outer segment. Red arrowhead, a TB microtubule. (D) Reconstructed model of microtubules in the outer segment. Blue, MO microtubule. White, TB microtubule. Red (tubule-A) + green (tubule-B), doublet. (E) Spatial distribution of microtubule ends in the outer segment. Every spot represented one end. Green, distal end. Red, proximal end. The yellow line (yellow arrowhead) indicates the distal tip. Scale bars (C–E), 500 nm. (F) The distribution of the distance between each microtubule end to the distal tip (representative of data from five cells). Red, proximal end. Green, distal end. The pie chart shows the percentage of MO microtubules that had the proximal end (p-end) in the TB. MT, microtubule; mem, membrane.