TEM pictures of Sonderia vorax : cell surface, cortex, and somatic ciliature. A. Ectosymbiotic bacteria cover the cell surface. Vesicles inside small cortical depressions are found in correspondence with ectosymbiotic bacteria. Slightly dense material is occasionally observed between ectosymbiotic bacteria and ciliate surface. Roots of monokinetids are visible: the kinetodesmal fibril, the postciliary microtubules, and the transverse microtubules. A Inset. Enlargment of a monokinetid root. B. The thick, dense epiplasm under the cortex; a dense body is visible inside somatic monokinetids. C. Bundles of subcortical microtubules (arrow). Abbreviations: db, dense body; dm, dense material; eb, ectosymbiotic bacteria; ep, epiplasm; exI, longer type extrusomes; kf, kinetodesmal fibril; pc, postciliary microtubules; t, transverse microtubules; v, vesicles. Scale bars = 0.5 μm.