[Ultrastructural changes in the rabbit aorta in early stages of experimental atherosclerosis]

First morphological (ultrastructural) signs of atherosclerotic changes in arteries have been shown to appear in the second week of keeping of rabbits on an atherogenic diet. They are manifested in the changes of "glycocalix" on the endothelium, disorders in the vessel wall permeability, distention and mucoid swelling of the subendothelial space, vacuolation of endothelial and smooth-muscle cells, and fragmentation of elastic fibers. The foamy cells appearing by 4 weeks of the experiment from the smooth-muscle cells migrating into the intima through fenestrations of the inner elastic membrane. As lipids accumulate, myointimal foamy cells undergo some ultrastructural changes such as swelling and loss of mitochondria, distention and vacuolation of the endoplasmic reticulum. Dystrophic changes are found not only in the intima of forming plaques but also in smooth-muscle cells of the adjacent parts of tunica media.