[The endothelium and arteriosclerosis].

The endothelium is of great importance in the development of early atherosclerotic lesions, as suggested from animal experiments. Denudation of the endothelium may stimulate the proliferation of smooth muscle cells which are a major constituent of sclerotic plaques. Furthermore, injury of the endothelium causing no morphologic alterations may be enough to induce secretion of endothelial-derived growth factors or attachment of monocytes/macrophages at the endothelial surface. Recent immunohistochemical studies indicate that monocyte-derived cells can be included in the endothelial layer, but the function of such non-endothelial cells is not yet known. Endothelial cells at the surface of advanced sclerotic lesions are often structurally abnormal. The endothelial patterns at the shoulders of stenotic lesions indicate blood flow irregularities, but on the other hand, the endothelium of the stenotic channel is suggestive of an unidirectional laminar flow. Atherosclerosis in humans is the touchstone of experimental atherosclerosis.