Coloured transmission electron micrograph (TEM) of the bacterium Helicobacter pylori (formerly called Campylobacter pyloridis). It is a curved, or spiral, Gram-negative bacilli with flagellae at that make it highly motile. Helicobacter pylori has recently been linked with the formation of stomach ulcers, through observation of the bacterium in biopsy specimens from patients with active chronic gastritis & peptic ulcers. Magnification: x11,000 at 6x4.5cm size.