Scanning electron microscopy of Neisseria gonorrhoeae. Age-induced changes in macro- and microstructure of virulent and avirulent colonies.

Virulent and avirulent gonococcal colonies were studied in the scanning electron microscope. Cells in virulent, in contrast to avirulent, colonies were found to be connected by numerous strands. After longer incubation periods, type 2 colonies segregated out regions of cells virtually lacking these strands. Cells within these areas probably represent avirulent segregants. The microstructure of individual colonies revealed no topographical differences. In certain colonies large smooth spherical cells were seen, probably representing wall-deficient gonococcal variants.