USE OF SMALL ANGLE X-RAY DIFFRACTION TO INVESTIGATE DISORDERING OF MEMBRANES DURING PREPARATION FOR ELECTRON MICROSCOPY .I. OSMIUM TETROXIDE AND POTASSIUM PERMANGANATE

1. 1. The influence of standard electron microscope OsO4 and KMnO4 fixatives, and some standard dehydration and embedding procedures, on the molecular structure of the myelin membrane of frog sciatic nerve were studied with a combination of small angle X-ray diffraction, electron microscopy and biochemical techniques. 2. 2. The observed periodicity and intensity changes indicated that re-arrangement of the membrane structure occurred with these fixatives. OsO4 and KMnO4 fixatives did not sufficiently stabilize the molecular structure, since subsequent acetone and alcohol dehydration agents produced large changes in the X-ray diffraction pattern of fixed nerve. These changes were associated with a considerable degree of extraction of cholesterol and a smaller degree of extraction of polar lipids. © 1969.