Bacteria on the tongue. Coloured Scanning Electron Micrograph (SEM) of unidentified colonies of bacteria on the surface of the tongue. These rod- shaped (bacilli) bacteria are coloured yellow. They are seen on stratified squamous epithelium of the tongue, flattened cells with blue borders. The cells have tiny folds (microplicae) on their surface which help the bacteria to adhere. The mouth and tongue supports a resident bacterial population, with most types of bacteria harmless and even useful. Some bacteria, however, may cause throat infections or form plaque leading to tooth decay. Magnification: x2,200 at 6x7cm size. x2,860 at 4x5 inch size.