Membrana limitans interna and epiretinal membrane lying on macular holes. Some morphological observations

The structure of the membrana limitans interna (MLI) in the region of the m acula has been investigated by electron microscopy in (a) 2 enucleated huma n adult eyes and (b) 38 surgically removed samples associated with an epire tinal membrane (ERM), In the enucleated eye, the glia cells were vitrad bor dered either by the lamina rara or, directly, by the lamina densa. Both ext ended into a coarse network whereby the lamina densa, through repeated bran ches and anastomoses, delimited large meshes, the lamina rara formed their contents. High magnification revealed that both meshes and contents of this network were composed by a further, finer network. It is suggested that st rips and small openings of the finer network are homologous to the cords an d intercordal spaces, respectively, which have been indicated as the common , basic structures of most of the basement membranes. The MLI excised with an ERM had the same structure. In some of the ERM associated with a macular hole, myofibroblasts prevailed among the cells. They showed indented nucle us, stress fibers abuting on the plasma membrane or in apparent continuity with bundles of extracellular filaments (microtendons), gap junctions. The cells lay on or were surrounded by a discontinuous basement membrane.