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Reorganization of the ependyma during axolotl spinal cord regeneration: Changes in intermediate filament and fibronectin expression
Author(s) -
O'Hara Christina M.,
Egar Margaret W.,
Chernoff Ellen A. G.
Publication year - 1992
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/aja.1001930202
Subject(s) - ependymal cell , vimentin , biology , intermediate filament , ependyma , glial fibrillary acidic protein , fibronectin , pathology , cytokeratin , microbiology and biotechnology , spinal cord , gfap stain , glial scar , astrocyte , anatomy , extracellular matrix , spinal cord injury , cytoskeleton , central nervous system , cell , immunohistochemistry , immunology , neuroscience , medicine , genetics
Changes in intermediate filament content and extracellular matrix material showed that the injury response of ependymal cells in lesioned axolotl spinal cord involves an epithelial‐to‐mesenchymal transformation, and that fibrous astrocytes are excluded from the remodeling lesion site. Antibody localization was used to visualize cytokeratin‐, vimentin‐, and glial fibrillary acidic protein‐ (GFAP‐) containing intermediate filaments, as well as the adhesive glyco‐protein fibronectin. In normal axolotl spinal cord cytokeratins were found near the apical surface of the ependymal cells. Transmission electron microscopic examination suggested that these cytokeratins were in tonofilaments. Cytokeratin expression was lost and vimentin production was initiated in ependymal cells 2–3 weeks following spinal cord injury. There was a period of approximately 1–2 weeks when cytokeratins and vimentin were co‐expressed in vivo. This co‐expression was maintained in vitro by culture on a fibronectin‐coated substratum. As the central canal reformed, vimentin expression was lost. Ependymal cells lacked GFAP intermediate filaments, but GFAP was present in fibrous astrocytes of the neuropil and white matter. Following injury, GFAP localization showed that fibrous astrocytes disappeared from the remodeling lesion site and reappeared only after the ependymal epithelium reformed and newly myelinated axons were found. Fibronectin expression closely followed the expression of vimentin during mesenchymal ependymal cell outgrowth. These results suggest that the ependymal cell outgrowth requires changes in cell shape followed by changes in production of extracellular matrix.