TEM pictures of Sonderia vorax : cytoplasm and nuclear apparatus. A. Various arrangements of hydrogenosomes-endosymbiotic bacteria. A few rod-shaped bacteria are visible in contact with hydrogenosomes. B. Various arrangements at a higher magnification; some association with the endoplasmic reticulum is visible. C. Rod-shaped bacteria in contact with hydrogenosomes and an obliquely cut longer type extrusome are visible. D. Hydrogenosomes not associated with endosymbiotic bacteria are sometimes visible strictly under the cortex, in clear correspondence with ectosymbiotic bacteria. E. A large food vacuole containing algae. F. Large paraglycogen granules, a portion of the macronucleus, and the micronucleus are visible; arrows point to a nucleolus. Abbreviations; a, algae; enb, endosymbiotic bacteria; er, endoplasmic reticulum; exI, longer type extrusome; fv, food vacuole; h, hydrogenosomes; ma, macronucleus; mi, micronucleus; pg, paraglycogen granules; rb, rod-shaped bacteria. Scale bars = 2 μm.