Electron microscopy of surface structures of Rickettsia prowazeki stained with ruthenium red.

In studying surface structures of Rickettsia prowazeki (E and Breinl strains) by ruthenium red staining, a microcapsular layer 125-165 A thick, composed of subunits 85--100 A in diameter with a periodicity of 100--120 A as well as the inner layer of the cell wall 40--60 A thick were clearly revealed. In tangential sections of cells, subunits of the microcapsular layer were found in parallel striation arrays. These structures presumably contain acid mucopolysaccharides detectable by ruthenium red staining. Besides, hitherto unreported intracytoplasmic membrane structures were detected in ruthenium red-stained rickettsiae.