False-colour transmission electron micrograph of Helicobacter pylori (formerly Campylobacter pyloridis). H. pylori is a rigid helical bacillus, differing from the genus Campylobacter in some of its morphology, such as the presence of terminal bulbs on the unipolar flagella (two seen here, centre). Unlike the Campylobacters, H. pylori has not been shown to be associated with gastroenter- itis. In recent research, however, H. pylori has been proposed as a co- factor for gastric cancer. Although not itself a causative agent, H. pylori may increase the chance of tumours arising. Magnification: x7, 700 at 6x4.5cm size.