Summary
Transection of the spinal cord in a series of Long Evans hooded rats results in a rapid degeneration of elements of the neuropil and white matter adjacent to the lesion site, and in the appearance of a wide variety of reactive cellular elements which ingest necrotic debris and produce a connective tissue matrix in the defect left by the lesion. Included among the non-neuronal elements found within the lesion zone and adjacent spinal cord segments cranial to the lesion were large clusters of ependymal cells displaced from their normal location. This aberrant proliferation produces extensive cords and nests of ependymal cells some of which maintain contiguity with those elements lining the central canal while other clusters were found several 100 μm distant in the gray matter. Rosettes with distinct lumina often occurred in such cellular aggregates and were similar in arrangement to those patterns displayed by primitive neuroepithelial cells following experimental manipulation (Watterson, 1965). Electron microscopy revealed typical oval euchromatin nuclei with a pale cytoplasm containing concentrations of filaments. Examination of rosette lumina revealed normal apical specializations including cilia with basal bodies, microvilli, and numerous zonulae adherentes Intracytoplasmic vacuole formation with abnormal microvilli and cilia were reminiscent of patterns described in certain ependymomas (Fu et al., 1974).
During the period between 15–45 days following injury, axons sprout into the scar matrix and along the adjacent, eroded cord segments. Those fibers which became apposed to the aberrant ependymal cells were enveloped by them and a typical “mesaxon” was formed. With increasing postoperative periods until 90 dpo, groups of 3–8 fibers could be found enclosed within a single cell.
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Matthews, M.A., St. Onge, M.F. & Faciane, C.L. An electron microscopic analysis of abnormal ependymal cell proliferation and envelopment of sprouting axons following spinal cord transection in the rat. Acta Neuropathol 45, 27–36 (1979). https://doi.org/10.1007/BF00691801
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DOI: https://doi.org/10.1007/BF00691801