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 fol
lowing results were obtained in normal rats. Epicardial arteries branc
h obliquely and run parallel to the outer surface of the heart. Arteri
oles emerging from these arteries run in different directions. They sh
ow a fold-like structure equipped with a prearteriole sphincter. The c
apillaries in the myocardium form a net-like architecture with many H-
like and Y-like anastomoses. Venous capillaries run directly into smal
l 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 arrange
d. 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.