Freeze-etch nomenclature for procaryotic bacteria

Abstract

A simple nomenclature for the freeze-fractured-etched membranes of procaryotic Gram-positive and Gram-negative micro-organisms is described. With a three letter code, the surface and fracture faces of the bacterial enveloping layers are clearly identified. The first letter defines the fracture face looking towards the bacterial cytoplasm (C) or the exterior (E), the second identifies structures as unfractured surfaces (S) or fractured faces of membranes (F) and the third locates the structure in the bacterial envelope.