Polymeric cryoproteetants in the preservation of biological ultrastructure

Abstract

Two high molecular weight polymers, polyvinylpyrrolidone (PVP) and hydroxyethyl starch (HES), have been used as cryoproteetants for preparing specimens to be freeze fractured. Solutions of 25% (w/w) suppress the formation of intracellular ice in single cells and tissue blocks from both plants and animals to the extent that fine structural details of the cell can be elucidated. The mode of action of these cryoproteetants, together with the structures they reveal and the peculiar advantages attached to their use, is discussed.