THE NON-DIRECTIONAL PATTERN OF AXONAL CHANGES IN WALLERIAN DEGENERATION - A COMPUTER-AIDED MORPHOMETRIC ANALYSIS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 139  (AUG) , 159-174
Abstract
Wallerian degeneration was investigated to determine whether axonal changes occurred progressively in a somato-fugal or somato-petal direction or simultaneously along the length of the axon. Microtubule density was used as a measure of the extent of axonal degeneration and was assessed by a computer-aided analysis of electron micrographs. The left sural nerves of 10 rats were crushed and 30 h later axonal areas and axonal microtubule numbers were recorded from a large sample of axons at 2 sites 1 cm and 3 cm distal to crush. The same recordings were made from the right unoperated nerve at 2 comparable sites. Statistical analysis of the whole data provided no evidence for a somato-fugal or reverse direction of degeneration. In Wallerian degeneration axonal changes, as indicated by microtubule dissolution, occur simultaneously along the length of the axon. To interpret the conflicting published data on the direction of fiber degeneration, Schwann cell changes (e.g., myelin ovoid formation) and axonal changes (e.g., microtubule dissolution) should be considered independently since they have different etiological mechanisms which may account for the differing experimental results reported.