Abstract: The objective of the study was to observe whether the pathologic changes of neuroretina were earlier than those of microvessels in Wistar rats in prodromal stage of diabetic retinapathy(DR). Male wistar rats,weighing about 200 g, were injected intraperitoneally with STZ at 60 mg/kg to create diabetes. The Wistar rats were decapitated at the time of one week, two weeks, one month after the model created and the retina was removed for electron microscopic observation of the retina and it's microvessel changes. In comparison with the normal controls, there are no obvious changes in the retina and the microvessel of the wistar rats during one week and two weeks with diabtes. In the Wistar rats after one month with diabetes,there were no changes in pigment epithelium layer, rod cell and cone cell layer, outer nuclear layer and microvessel basement membrane and perivascular cells, but there were obvious pathologic changes from outer plexiform layer to neurofibrous layer: swelling and deformity of mitochondria, shortening and disappearance of cristae, medullary degeneration of mitochondria were seen, and the number of mitochondria were reduced. There was obvious neuron cell tuber edema in neurofibrous layer, outer and inner plexiform layer, especially in neurofibrous layer. Dark cells were seen in ganglionic layer. As a result of the edema, some adjacent microvessels were oppressed to be stenosed or even atretic. In the early stage of DR, there is no retina microvessel damage when retinal neuron damage happens. The retinal neuron damage could be the early sign in the progress of DR.

Key words: diabetic retinopathy, neurortetina, pathologic change