Histochemistry and ultrastructure of gastric submucosal vasculature in portal hypertensive rats.

We studied histochemical and ultrastructural characteristics of the gastric submucosal blood vessels in portal hypertensive (PHT) rats. PHT was induced by two-stage ligation of the portal vein. Control rats were sham operated (SO). On the fifth day after surgery portal vein blood pressure was measured and rats were killed under nembutal anesthaesia. Gastric specimens were obtained for histological, histochemical and ultrastructural assessment. PHT rats showed thickening and increased cellularity of submucosal vessels including increase in number and size of endothelial cells. All these mesenchymal cells were vimentin-positive. Thickening of vascular wall in submucosal vessels was also observed ultrastructurally together with prominent elaboration of luminal surface of endothelial cells. These changes were not observed in SO rats. All changes in PHT rats reflect vasculopathic involvement of gastric wall in portal hypertension.