ULTRASTRUCTURAL CHANGES OF ENDOTHELIUM IN UNSTABLE ATHEROSCLEROTIC PLAQUES OF CAROTID SINUS
6 unstable atherosclerotic plaques obtained from subjects undergoing carotid endarterectomy were examined using light and electrone microscopy. There were 2 symptomic and 4 asymptomic plaques. A wide range of endothelium ultrastructural changes was established. Deendothelized areas were common, hypertrophied endotheliocytes with increased metabolic activity and features of hydropic degeneration of various degrees predominated. The fraction of activated cells increased with a reduction of elastica quantity, increase of oedema and fiber decomposition in subendothelial layer, volume fraction of atheromatosis in the atherosclerotic plaque. Activated endotheliocytes were characterized of an amplification of luminal and basal surface associated with cytoplasmic processes formation, hyperplasia of rough endoplasmic reticulum and Goldgi complex, increase in both the number and the size of mitochondria, increase or decrease in the number of micropinocytotic vesicles with a tendency towards clustering and multivesicular complexes formation, swelling of cells, simplification and shortening of interendothelial junctions, weakening of connections to underlying matrix. It has been established that the fraction of activated endotheliocytes was significantly higher in symptomic compared to asymptomic plaques.