Autolytic changes of human white matter: an electron microscopic and electrophoretic study

The effect of autolysis on the electrophoretic pattern of the 3H-labeled membrane glycoproteins derived from human brain white matter (WM) was investigated and correlated with electron microscopic findings. Samples were taken from the WM of outer zones of routine surgical specimens sent for pathologist's examination. The WM samples were incubated at +4 and +25 degrees C for 6 and 24 hr and analyzed by electron microscopy and by galactose oxidase labeling with subsequent SDS-polyacrylamide gradient gel electrophoresis. The effect of freezing and thawing was also studied. In electron microscopic examination myelin was found to have degenerated after an incubation of 24 hr at +4 and +25 degrees C, and it was severely disrupted after 24 hr at +25 degrees C, when a periaxonal network-like change was observed. The major labeled membrane glycoprotein band with an estimated molecular weight (MW) of 138,000 was stable during the first 24 hr of incubations at both +4 and +25 degrees C. No marked changes were noticed in the electrophoretic pattern of all of the WM membrane proteins labeled by [3H]acetic anhydride technique. In frozen and thawed specimens there was an increase in the intensity of the band with a MW of 86,500 and a new band appeared at the MW region of 25,000. The present results suggest that despite the apparent stability of the major glycoprotein band during the first 24 hr of autolysis, there are ultrastructural abnormalities in the myelin sheath, which should be taken into consideration during interpretation of changes in pathologic conditions.