Four different views of a surface-rendering representation of the 3D model of IFT particles in fla14 flagella. Colors have been assigned to subvolumes of the density map corresponding to different flagellar structures using the same color coding shown in Figs. 5 and 6 (white, flagellar membrane; red, IFT particles; yellow, MT doublets). In this and subsequent figures, the images are oriented so the flagella point down or to the right. (a) The white lines highlight the festooned profile of the IFT particles. The same wave pattern is seen in Fig. 6, panel 1, and Fig. 2 (f–o). (b) Cross-section view of the same model oriented so that the tip of flagellum points toward the reader. The white arrows indicate the position of the links between each IFT particle and the B subtubule of the MT doublet (B). A, A subtubule of the MT doublet. (c) Three pairs of IFT particles lying on the flagellar membrane (white wire net pattern) as seen from the interior of the axoneme. Oblique links (d) connect neighboring particles (white ovals) along each strand. Links (l), oriented parallel to the longitudinal axis of IFT trains, connect the heads of adjacent particles. The position of the links between IFT particles and the B subtubule of the MT doublet are labeled with a k, and may be the kinesin-2 motors. (d) The pairs of IFT particles as seen from the exterior of the flagellum. The yellow net behind them represents the outer surface of an MT doublet. 1, 2, 3, and 4 indicate the contact points between IFT particles and the flagellar membrane. Video 2 shows a rotation of the surface-rendered model.