[Scanning and transmission electron microscopy findings in the coronary vessels in physiologic and pathologic states]

Scanning and transmission electron microscopic examinations of the coronary vessels were performed on rats, and the findings compared. Both procedures demonstrated a tightly meshed network of arterial endothelium orientated to the direction of flow, thereby allowing optimal adaptation to changes in direction of blood flow, high intervascular pressure, structures of the remaining intima components and variable states of arterial wall tension. Venous endothelium proved to possess a markedly less uniform constitution, the texture of the inner surfaces being strongly determined by the surrounding perivascular tissue. Induction of arterial hypertension in rats (via GOLDBLATT-hypertension) and in Cynomolgus monkeys (via aortic constriction), and hyperlipidemia in hypertensive rats through a fatty diet enabled the study of a wide spectrum of coronary artery endothelium disease, primarily at early stages. Both species demonstrated hypertensive endothelial dehiscence (gaps), basically passive in nature and due to increased endothelial mobility. Occasionally, peculiar cytoplasma deformations could be found surrounded by circumscribed, consecutive endothelial gaps, allowing speculation of increased contraction-like states of intraendothelial filament tension due to hypertension. Areas of intima damage were usually focal and demonstrated numerous degenerative endothelial changes, endothelium necrosis and defects. Small endothelial gaps were covered by a film of thombocytes, though this finding was seen only in monkeys. Attempts at endothelium regeneration and reparation were manifest in increased endothelial mitosis, pseudoendotheliums, endothelial giant cells and films of leucocyte aggregations covering endothelium defects. Migration of leucocytes into the intima was actively furthered through small leaks in the endothelium. Hyperlipidemic and hypertensive rats showed endothelial bloating, due in part to vacuolar intracytoplasmatic lipid deposits with phagocytosis of fine particles of cholesterin crystals.(ABSTRACT TRUNCATED AT 250 WORDS)