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Abstract
The electron microscopical appearance of the capillaries and pericapillary glia have been studied in retinas subjected to osmotic changes and compared with that of normal ones. These experiments were carried out in cats, and the osmotic changes were induced by the local application of distilled water or hypertonic saline in vivo. After the application of distilled water, we found that the capillary lumina were narrowed or even closed by swelling of the endothelial cells and pericytes; while, after the use of hypertonic saline, the capillary lumina were luidely open because of capillary cell shrinkage. These results were in accord with our intravital observations,1 and suggested that variations in the size and shape of the endothelial cells may have been factors regulating the blood flow in the capillaries. Our experiments indicated that an extracellular space existed in the retina, and this was narrowed after the application of distilled water, and enlarged after the use of hypertonic saline.