Electron Microsopic study of Diabetic Preretinal Membranes

ABSTRACT

We conducted electron microscopic observation of twenty diabetic preretinal membranes removed during vitrectomy. Membranes were composed of many different types of cells and vessels and intercellular substance. Vessels of develping stage had forming narrow lumen and endothelium showed pinocytic vesicles and apical microvilli, and surrounded with vascular pericytes and multilayed basement membrane. Vessels of mature stage had large lumen and endothelium was flat. In vessels of regressing stage, lumen was obstructed with plug of red blood cells and endothelial cells were degenerating with abundant residual bodies. Pericytes also showed degenerative change. Most of junctions between endothelial cells wer tight junciton in all stage of vessels, but incomplete form of tight junction with open intercellular cleft was found more frequently in vessels of immature stage. Cells found in membranes were fibroblast, macrophage, myofibroblast, fibrous astrocyte in frequency. Extravascular plasma cell and polymorphonuclear leukocytes were observed occasionally. Intercellular substance was lagely composed of mature collagen. These results suggest incomplete endothelial junctions may be partly responsible for permeability of diabetic new vessels, and degenerated endothelium and pericyte may contribute to vitreous hemorrhage.