[Biopsy data on the ultrastructural changes in the cerebral cortex in Vilyui encephalomyelitis].

Biopsies from the cortex of the right frontal lobe of 3 patients with chronic Vilyui encephalomyelitis were examined light- and electron microscopically. The characteristic degenerative changes in the gangliocytes and especially in the nerve fibers are typical for this disease; particularly severe lesions were found in the myelin sheaths and to a lesser extent in the axons. Myelin sheaths lamella, external mitochondrial membranes and other organelles showed osmiophilic degeneration with their destruction and release of peculiar crystal-like formations having an elective localization in the processes cytoplasm and not in the perikaryon. Abnormal chromatin agglomeration, increase in size and ectopy of nucleoli were observed.