TEM pictures of Sonderia vorax : somatic ciliature and extrusomes. A. Monokinetids (in longitudinal section) with two serial terminal plates (asterisks) alternate with longer type extrusomes. These show a layered inner structure in longitudinal section (also visible in D, F--H). According to pictures, longer type extrusomes in five different stages are visible: developing (H), not yet docked (D), almost docked (A), resting (G), about extruding (F). B, C. The somatic monokinetids in cross (B) and longitudinal (C) section and part of their fibrillar associates: the kinetodesmal fibril and the postciliary microtubules; a slightly dense material is present between cortex and ectosimbionts E. Longer type extrusomes in cross and oblique section. G, G Inset. A second type extrusome in longitudinal section near a longer type extrusome. Abbreviations: cl, clear layer; co, core; dm, dense material; exI, longer type extrusome; exII, second type extrusome; kd, kinetodesmal fibril; gl, glanular layer; ho, hood; m, extrusome membrane; pc, postciliary microtubules. Scale bars = 0.5 μm.