Aortic lesions in nonlaying hens with endogenous hyperlipidemia.

Atherogenicity of chemically discrete cholesterol has been questioned earlier at small doses insufficient to cause hypercholesterolemia. Long-term experiments involving large doses are hindered by the propensity of cholesterol to autoxidize in air. As an alternative, aortic lesions in mature, 1- to 3-year-old laying and hereditary nonlaying hens were studied by electron microscopy. Due to spontaneous egg yolk involution, serum cholesterol values of nonlayers were high, averaging 583 mg/dL, and triglyceride values averaged 1,777 mg/dL. Respective values in layers were 106 mg/dL and 894 mg/dL. Aortic lesions in nonlayers developed earlier and were more extensive and fatty than in layers. Lipids were stainable even in the media of grossly normal segments of aorta in nonlayers. Findings suggested an important role of inhibition of hyperlipidemic components. It is unknown, however, whether large amounts of endogenous cholesterol in serum undergo autoxidation in vivo.