Ordering in the Nerve Membrane

The ultrastructure of neuronal cells has been studied employing a variety of techniques. The structural details of a native axon are, however, still far from being elucidated. 

Electron diffraction patterns have been obtained of myelin and rat central nervous system membranes after osmium tetroxide and formalin fixation. Strongly diffractive crystalline material present in an OSO4 fixed specimen was interpreted as precipitated dye as the observed spotted pattern was much weaker in formalin treated tissue samples. OSO4 easily reacts with ethylenic double bonds. An alternative and more likely explanation therefore is that regular, electron dense crystalline structures are formed due to reaction of OSO4 with a highly organized lattice of unsaturated membrane lipids. 

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