Ultrastructural characteristics of epiretinal membranes]

To investigate ultrastructural features and the correlation between the cell activation and extracellular matrix (ECM) expression of epiretinal membranes.Immuno-electron-microscopy was done on the epiretinal membranes removed by vitrectomy from 16 patients with rhegmatogenous retinal detachment associated with proliferative vitreoretinopathy (PVR). The specimens were stained with antibodies to ECM proteins, including type I collagen, type III collagen and fibronectin (FN).A type of cells with a number of lamellipodia was found in membrane sections of 9 patients. The lamellipodia appeared to be either coiled or branched and were surrounded by abundant collagen fibers of type I and III. The cells with lamellipodia varied in their phenotypes and with or without pigment. There were dense gold particles of FN in contact regions of lamellipodia and collagen.Our observations support that the contraction of epiretinal membranes is the result of an interaction between cells and collagen, and the cells extending lamellipodia may initiate contractile events. FN is responsible for this contractile action.