Demonstration of the Sjöstrand Membrane Particles by an Electron Cytochemical Method

Abstract

RECENTLY, several reports^1–3 have appeared which convincingly demonstrate that certain membrane systems of the cell are composed of a sub-unit structure somewhat out of accord with the classical triple-layered unit membrane structure previously proposed by Robertson⁴. These data, presented by Sjöstrand, have shown that mitochondrial membranes are composed of globular elements with a diameter of about 50 Å between which are situated septa as thin as 10 Å in thickness. From these observations, which were gained from osmium-fixed, permanganate-fixed and also frozen-dried material, Sjöstrand put forward a theory for the molecular architecture of the mitochondrial membrane. Included in this scheme was the idea that lipid molecules comprise the globular micelles, and that the septa consist of protein molecules, which, specifically in mitochondria, would include enzymes of the electron transfer chain such as the succinic dehydrogenase system (SDH).