USE OF SMALL ANGLE X-RAY DIFFRACTION TO INVESTIGATE DISORDERING OF MEMBRANES DURING PREPARATIONS FOR ELECTRON MICROSCOPY .2. ALDEHYDES

1. 1. The influence of some standard electron microscope aldehyde fixatives on the molecular structure of myelin membranes of frog sciatic nerve was studied with a combination of small angle X-ray diffraction, electron microscopy and biochemical techniques. 2. 2. Small angle X-ray diffraction was found to be very useful for the study of aldehyde fixation, since the absence of a heavy metal allows a direct interpretation of diffraction patterns. 3. 3. It was shown that conventional aldehyde fixatives introduced changes in the diffraction pattern of fixed nerve. Conventional acetone and alcohol dehydration introduced large changes in the diffraction patterns of fixed nerve, apparently as a result of significant extraction of both polar and non-polar lipids. 4. 4. Modified fixation, dehydration and embedding techniques are described. The electron microscope appearances are described of myelin embedded with some water-soluble embedding materials in which lipid extraction is significantly reduced. © 1969.