Endothelial lesions in the aorta of egg yolk-fed miniature swine: A study by scanning and transmission electron microscopy

Evidence has been accumulating which suggests that atherosclerotic lesions are preceded by endothelial cell damage. Ten miniature swine (FDA, Beltsville, Md.) were maintained on an egg yolk diet (six animals) or on a control diet (four animals) beginning at 5 weeks of age. All animals were sacrificed at 52 weeks of age by intracardiac perfusion of glutaraldehyde. Segments of the aortae were excised and prepared for scanning (SEM) and transmission (TEM) electron microscopy. SEM examination of the aortae of egg yolk-fed animals revealed crater-like defects in the endothelial surface associated with marked cellular deformation and disruption. With TEM there were areas of focal disruption of the luminal plasma membrane and exposure of subendothelial tissues. These alterations were found most commonly on or near the leading or following lip or lateral to branch orifices. Similar endothelial lesions (crater-like defects) have been found in monkey and rabbit arteries following ischemia and in rabbit arteries following cholesterol feeding, epinephrine injection, mechanical trauma, and delayed fixation. It is believed that these alterations are a nonspecific reaction of endothelial cells to injury and may represent the initial morphological abnormality in the pathogenesis of atherosclerosis.