False-colour transmission electron micrograph of spherical bacteria Chlamydia sp., (brown dots) in the cytoplasm of a cell. A genus of virus-like microorganisms that cause disease in man & birds (unlike most bacteria Chlamydia lives & grows only inside cells). Chlamydia trachomatis is reponsible for some 50% of cases of non-specific urethritis (NSU) in the U.K. (which if untreated may lead to serious pelvic inflammatory disease in women, possibly leading to sterility). When diagnosed early, Chlamydia is easily treated with a 2-3 week course of antibiotics tetracycline or erythromycin. Magnification: X 2,000 at 35mm size.