ABSTRACT
Objective To investigate the ultrastructural changes of retinal pigment epithelium (RPE) and its permeability in spontaneously hypertensive rats (SHR) and explore the relation between these changes and hypertensive retinopathy. Methods The ultrastructure of RPE cells in the SHR aged five、six、seven months was observed with transmission electronmicroscope and compared to its normotensive control strain(WKY) with the same age.Then, lanthanum tracer procedures were carried out to investigate pathological changes of the blood retinal barrier. Results ①In SHR the main pathological changes involved swelling of mitochondria, enlargement of endoplasmic reticula,decrease of RPE cell infolding, and sparseness of microvilli. These degenerations were more serious in older rats with higher blood pressure.②The breakdown of outer blood retinal barrier with permeation of lanthanum tracers were evident in SHR aged six or seven month, however, in WKY and five month SHR the traces were preven ted from passing by tight junctions. Conclusion The degeneration of RPE owing to ischemia and anoxia arises in early period of hypertensive retinopathy. The pathological changes of ultrastructure and permeability might interact with the damage of visual cells and play a main role in the hypertensive retinopathy.