Demonstration of extracellular material at the surface of pathogenic T. pallidum cells.

Pathogenic T. pallidum cells possess and extracellular layer when observed in vivo and in vitro after exposure to ruthenium-red. The extracellular layer is partially removed from a pre-fixed cell by repeated washing in vitro. Non-pathogenic treponemes examined in this study do not possess an extracellular layer. It is hoped that the data presented herein will cause our colleagues to take another look at the methods and techniques used for preparing pathogenic T. pallidum cells for practical end-point objectives.