False-colour transmission electron micrograph of a Neisseria gonorrhoeae bacterium undergoing binary fission. N. gonorrhoeae bacteria are the cause of the sexually-transmitted disease gonorrhoea. They are Gram-negative, non-motile & kidney-shaped & often occur in pairs. Infection occurs through the genital mucous membranes of either sex. Symptoms include pain on passing urine & a discharge of pus from the penis or vagina, though some women may experience no initial symptmoms. Untreated, the infection spreads & may cause sterility in women & urethral blockage in men. Magnification: x48,000 at 6x4.5cm size.