Myelin structure transformed by dimethylsulfoxide.

X-ray diffraction patterns from nerves bathed for about one-half hour in Ringer's solution containing dimethylsulfoxide at concentrations of 10% or more show reflections from a new, highly ordered structure with a repeat period about two-thirds that of native myelin. The proportion of myelin transformed is greater at higher concentrations, and above 40% the native pattern is no longer observed. Replacing the dimethylsulfoxide with Ringer's solution leads to the rapid reappearance of the native diffraction pattern. The effect of dimethylsulfoxide can be accounted for by the loss of water from the spaces between the membrane units without significant modification of the bilayer structure.