Neisseria meningitidis pili

Neisseria meningitidis is a leading cause of bacterial meningitis, a potentially lethal disease that affects both children and adults. The bacteria use adhesive organelles called Type IV pili which help them interact with each other to form colonies and adhere to the surface of epithelial cells in the human nasal tract. Pili can be several microns in length, but are only 7 nm in diameter. In this image, the bacteria have been stained with salts of uranium to increase contrast in the electron microscope. Individual pili can be seen radiating from the bacterium, in addition to outer membrane vesicles that have been shed by the bacteria.