Coloured transmission electron micrograph of the bacteria Bacteroides gingivalis (formerly Bacteroides melaninogenicus asaccharolyticus). These Gram-negative, anaerobic bacteria are rod- shaped cocco-bacilli. The thick cell wall is seen, with cell contents, and some bacteria are undergoing division. B. gingivalis is associated with gingivitis (gum disease) & other periodontal infections including ulcerative gingivitis and mouth abscesses. This bacteria is not confined to to the mouth and may infect other regions of the body. In humans it also occurs as normal harmless flora in the mouth, intestine & urogenital tract. Magnification: x30, 240 at 6x4.5cm size.