Morphological studies of angiosarcomas induced by 1,2-dimethylhydrazine dihydrochloride in Syrian golden hamsters.

Studies were made on the morphological characteristics of blood vessel tumors induced by the p.o. lifetime administra tion of 0.001% 1,2 dimethylhydrazine dihydrochloride in Syrian golden hamsters. The lesions were classified as angiosarcomas. They occurred in 89% of the females and 82% of the males (with decreasing frequency) in liver, lungs, muscle, heart, and pancreas. Gross, light, and electron microscopic and histochemical investigations were performed on the tumors. The macroscopic and light microscopic study showed the typical appearance of angiosarcoma composed of round or elongated polygonal neoplastic endothelial cells which formed vascular spaces and clefts. The histochemical work included the determination of collagen, reticulum, ionized iron, polysaccharide-mucopolysaccharide-glycolic fatty acid content, and alkaline phosphatase enzyme activity by the lesion. The formation of reticulum and ionized iron was negligible, while the amounts or the activity of the other three substances were substantial. Electron microscopic examination revealed the ultrastructural details of the various components of the vascular lesion including part of its developmental stage. Hemorrhagic areas, structural characteristics of the angiosarcoma, malignant endothelial cell nucleus with chromatin arrangements, and its cytoplasm with organdÃ-es,intraluminal cell surface, and contact between neoplastic endothelial cells are described and illustrated.