Scanning Electron Microscopic observations of endothelial changes in experimentally induced atheromatosis of rabbit aortas

Abstract

Following the administration of cholesterol for a period of 6-7 weeks, Scanning Electron Microscopic (S.E.M.) observations revealed mono-cellular, crater-like and dome-shaped endothelial changes on top of the large intimal plaques in the rabbit aortas. Finger-like and other shaped cell protrusions were observed at the edges of these crater-like and dome-shaped endothelial changes, giving the intimal plaques a rough appearance. At other sites, normal, smooth, although irregularly arranged, endothelial cells covered the lesions. By impregnating the cell borders with silver-nitrate or silver proteinate containing perfusates, it was possible in most cases to ascertain that the lesions were derived from changes in one cell or from changes in a small collection of cells. S.E.M.-observations further revealed crater-like and dome-shaped endothelial changes to be present in large fields or as isolated cell changes in normal areas at sites where no gross lesions were observed with the light microscope. In addition large, multi-cellular, crate-like endothelial changes were observed at the edges of the large intimal plaques. At these sites several endothelial cells were lacking, leaving behind a crater in which sometimes cells and a few fibrin threads were found. Following the administration of cholesterol for periods of 4-5 and 2-3 weeks similar monocellular changes were observed, some extending over large areas, other as single cells in apparently normal surroundings. Quantitatively the number of lesions was less than when the cholesterol was administered for a longer period. Transmission electron microscopic studies revealed the presence of large amounts of membrane-bound lipid globules in the subendothelial spaces and within some endothelial cells, structures which were assumed to be cross-sections of the crater-like or dome-shaped endothelial cell protrusions, visible with the S.E.M.

Endothelial Structure in Rabbits With Moderate Hypercholesterolaemi

“…Scanning electron microscopy has also previously been employed to study endothelial ultrastructure in dietarily induced experimental atherosclerosis (Weber & Tosi 1971a, b, Weber et al 1974, 1975, Still 1974, de Bruijn & van Mourik 1975. However, when these studies were performed, attention had not yet been called to the ready production of artefacts in the preparation procedure for scanning electron microscopy.…”

“…In view of this it is possib!e to comprehend data suggesting that endothelial integrity is decreased in the centre of lesions. Investigators presenting such data have studied very early lesions (Weber & Tosi 1971 a, b, Weber et a1 , de Bruijn & van Mourik 1975. It is possible that re-endothelialization may not yet have occurred in such lesions.…”

Problems with the preparation of blood vessels for scanning electron microscopy a critical review

“…In recent years the perfusion method has prevailed more and more (Buss et al 1973, Buss and Hollweg 1977, Buss et al 1976, DeBruijn and VanMourik 1975, Edanaga 1974, Elemer et al 1976, Fishman et al 1975, Fonkalsrud et al 1976, Frenzel et al 1976, Hess and Staubli 1963, Shimamoto 1974, Svendsen and Jorgensen 1978, Webster et al 1974). Unfortunately there are also additional methodological variations and possibilities of error involved in this more complicated technique, making comparisons more difficult.…”