Transmission electron microscope images of Cepedea longa, to show fine structures of the somatic flagella. (A) Tangential section of a somatic kinety, to show fibrillar elements (arrow) between cortical microtubules (Mt) and around the membrane of each flagellar pit (FP). PF = pellicular folds. Scale bar = 2.5 μm. (B)–(C) Cross section through several kineties, to show somatic kinetosomes (SK) linked by desmoses (Ds) and sometimes interposed by vacuoles (V) just beneath the cell surface. A = kinetosomal arms. Scale bar = 2.5 μm. (D) Longitudinal section of kinetosomes, to show detailed fine structures. The axosome (Ax) is embedded in the proximal margin of transitional discs (TD), with curving arms (A) extending out and up. H = transitional helix, Mt = microtubules, SK = somatic kineties, PF = pellicular folds, FP = flagellar pit. Scale bar = 5 μm.