INITIAL STRUCTURAL LESION IN SERUM-INDUCED DEMYELINATION INVITRO

  • 1 January 1976
    • journal article
    • research article
    • Vol. 35  (4) , 391-401
Abstract
Myelinated cultures of mouse spinal cord were exposed to sera obtained from rabbits affected by experimental allergic encephalomyelitis following challenge with whole white matter in complete Freund''s adjuvant. In the presence of complement, the tissue response begins with an increased birefringence of its myelin sheaths. This is rapidly followed by a gamut of changes leading to demyelination. In the absence of complement, the response is arrested at the stage of increased birefringence. This early stage of the demyelinating process was available for detailed examination by light microscopy and EM. The brightened myelin sheaths appeared within a few hours of exposure and were seen around all axons and sometimes around cell bodies. This was often accompanied by abrupt breaks in the sheaths and angularly shaped myelin figures. Examination by EM revealed a uniform increase in the myelin period from 11-22 nm. The normally double intraperiod line was increased to 4 electron-dense leaflets, the additional 2 appearing to be derived from the close apposition of an additional electron-dense layer on the outer surface of the myelin sheath or oligodendrocytic membrane. Oligodendrocytes responded with a prolific growth of processes whose membranes compacted to form swollen myelin. Neurons, astrocytes and neuropil showed no changes. In its early stages, at least, the swelling was reversible. The 1st stage of antiserum-induced demyelination in vitro, a stage now available for further study, was apparently isolated.