Ultrastructural study of crossbands occurring in the stalks of Caulobacter crescentus.

An ultrastructural study of crossbands isolated from Caulobacter crescentus Sk1 418 stalks permitted a view of these structures in a plane other than the perpendicular view normally presented in the electron microscope. These crossbands were composed of concentrically arranged, alternating light and dark bands when stained with phosphotungstic acid. Evidence supports the hypothesis that crossbands appear to compose a structural barrier extending the width of the stalk and may function to support unit membrane extending the length of the stalk.