Fig. 4. Formation and movement of the FC in the absence axonemal assembly. (A) A thin-section electron micrograph shows formation of a FC (asterisk) in the flagellar pocket of a TbCHE2 RNAi-induced cell. (B,C) Thin-section electron micrographs revealing the extrusion of flagellar membrane (arrows) beyond the flagellar pocket of TbCHE2 RNAi-induced cells and the formation of macula adherens junctions within the FAZ (white arrowheads within a square bracket). nf, new flagellum. (D-I) Exit of a flagellar stub from the flagellar pocket and the left-handed helical twist of the flagellar sleeve in TbCHE2 RNAi-induced cells as revealed by scanning electron microscopy. The boxed regions of D,F,H are shown at higher magnification in E,G, and I, respectively. of, old flagellum; arrows point to the flagellar sleeve. (J) The elongating new flagellum is positioned on the left-hand side of the old flagellum in cells with two flagella. (K) Transverse section through a TbCHE2 RNAi-induced cell reveals the presence of a flagellar sleeve (arrow) to the left-hand side of the old flagellum and is attached by a FC. Bars, 500 nm (A,B,E,G,I,J); 2 µm (D,F,H); 200 nm (C,K).