Glial epiretinal membranes and contraction. Immunohistochemical and morphological studies
Y. N. Hui, R. Goodnight, X. J. Zhang, N. Sorgente and S. J. Ryan
Department of Ophthalmology, University of Southern California School of Medicine, Los Angeles.
It has been suggested that glial cells do not contribute substantially to
the contractile forces generated by epiretinal membranes. We have
established a rabbit model in which epiretinal membranes form on the
inferior peripheral retina after the injection of activated macrophages
into the vitreous. By two months, the membranes were extensive but without
evidence of traction. At four months, however, full-thickness retinal folds
were present beneath the thick epiretinal membrane. A homogeneous glial
cell composition was suggested by light microscopic examination of serial
sections through several membranes. Immunohistochemical staining with
anti-glial fibrillary acidic protein and antivimentin and immunoelectron
microscopy confirmed that these thick epiretinal membranes were composed
entirely of glial cells, which may cause mild traction on the retina; this
traction is associated with cell alignment and the tissue bridges
connecting the membrane and the retina. The fusiform densities and indented
nuclei suggested that the glial cells within the membrane may possess some
characteristics of myofibroblasts.
