FE-SEM images reveal healthy spiral morphology of Hp cells cultured under aerobic condition. Hp 26695 was cultured in liquid medium with shaking under 2%, 8%, or 20% O2 tension in the absence or presence of 10% CO2. Cells harvested at 12 or 36 h were visualized by FE-SEM. Examples of spiral (S), bacillary (B), U-shaped (U), rounded (R), and coccoid (C) forms are indicated. In enlarged pictures, outer membrane vesicles can be seen on cells cultured under 20% O2 tension for 12 h, but not cells cultured for 36 h. Data shown are representative of three independent experiments. Scale bar = 1 μm.