Morphological changes of the villous microvascular architecture and intestinal growth in rats with streptozotocin-induced diabetes.

Using intact tissues and vascular corrosion casts, morphological changes in the small intestine of streptozotocin-induced diabetic rats present 1 month after onset were investigated using scanning and transmission electron microscopy. Although there were increases in the height of the villi in the jejunum and not in the ileum, characteristic changes in surface morphology in the diabetic rats were observed only in the ileum. Use of a vascular corrosion cast technique clearly demonstrated the prominent thick marginal vessels of the intestinal villi of the control rats. In the diabetic rats, the central arterioles in the villi were dilated both in the jejunum and the ileum. Marginal vessels were small in the ileum but prominent in the jejunum. Using transmission electron microscopy, decreases in diameter and the number of endothelial fenestra were also evident in the marginal vessels of the ileal villi in the diabetic rats. Thus in rats made diabetic, fine structural alterations of the marginal vessels are induced in the villi of the distal ileum, in addition to quantitative changes in the jejunal villi, presumably related to hyperphagia. The marginal vessels seem to be involved in the regulation of microcirculation of the intestinal villi in the rat.