Angioarchitecture in the heart of rats with streptozotocin-induced diabetes mellitus.

The effects of chronic streptozotozin-induced diabetes mellitus on the angioarchitecture of the heart in male Wistar rats were studied with the use of cast preparations and scanning electron microscopy. The following results were obtained in normal rats. Epicardial arteries branch obliquely and run parallel to the outer surface of the heart. Arterioles emerging from these arteries run in different directions. They show a fold-like structure equipped with a prearteriole sphincter. The capillaries in the myocardium form a net-like architecture with many H-like and Y-like anastomoses. Venous capillaries run directly into small veins at right angles while venules converge to form small veins at acute angles. In rats which have been suffering from diabetes mellitus for 8 months the capillary system appears less systematically arranged. The venous system generally exhibits dilatations. Dilatations were also seen along capillaries at short distances. In rats which had had untreated diabetes mellitus for 2 months and then 6 months of insulin treatment, a dilatation of the whole venous system was seen, but there were no significant changes in the capillary system.