Retinal and epiretinal glia--an immunohistochemical study.

Immunohistochemical techniques were used to examine the distribution of cells containing glial fibrillary acidic protein (GFAP) in normal and pathological human specimens, including 22 globes (13 of which contained epiretinal membranes 'in situ'), 16 surgically excised epiretinal membranes, and monolayers of cells obtained from five epiretinal membranes placed in tissue culture. The astrocytic cells of normal and pathological retinae stained with the glial-cell marker, but Müller cells were GFAP-negative in normal retinae at the antisera dilutions used. Müller cells did, however, stain in retinae from glaucomatous eyes and in eyes with prolonged retinal detachment. Electron microscopy did not reveal any obvious morphological difference between the intermediate filaments of normal (GFAP-negative) and GFAP-positive Müller cells. Ten of the 13 epiretinal membranes 'in situ', all 16 excised membranes, and three of the five monolayers contained glial cells. Purely glial membranes were not associated with retinal puckering or detachment, while all membranes causing tractional complications had a prominent fibrous, non-glial component. Our findings suggest that glial cells do not contribute significantly to the contractile forces generated by epiretinal membranes. They may, however, provide a scaffold on which other cells proliferate and contract and an anchorage by means of which tangential forces are transmitted into and through the retina.