RESUMEN
The concept of atherosclerosis is essentially applicable to the arteries of the elastic type. Lesions in the arteries of the muscular type have a different character. They show an association of fibrosis of the media with a diffuse intimal thickening and the presence of stratified fibro-hyaline plaques, representing organized parietal thrombi. Deposition of lipids is weak or moderate and apparently a secondary event. Intimal thickening of peripheral arteries exceeds largely the limits of the thrombotic zone. It is covered by normal endothelium and populated by myocytes with a few fibroblasts. The intercellular substance shows all stages of formation of elastic structures, a process which is probably related to the activity of myocytes. It leads to the formation of one or several fairly distinct elastic membranes. Concomitantly the lamina elastica interna undergoes considerable degradation. We are, thus, confronted with a lesion of considerable age which, nevertheless, remains active and shows continuing structural changes. The origin of cells in intimal thickening and its significance in terms of general pathology are discussed with respect to the experimental results.
Asunto(s)
Arteriopatías Oclusivas/patología , Trombosis/patología , Adulto , Anciano , Arteriosclerosis/patología , Arteriosclerosis Obliterante/patología , Femenino , Arteria Femoral , Humanos , Arteria Ilíaca , Pierna/irrigación sanguínea , Masculino , Persona de Mediana Edad , Arteria PoplíteaAsunto(s)
Endarteritis/patología , Arteria Femoral/patología , Animales , Endotelio/ultraestructura , Espacio Extracelular , Arteria Femoral/ultraestructura , Fibroblastos/ultraestructura , Histiocitos/ultraestructura , Masculino , Microscopía Electrónica , Músculo Liso Vascular/ultraestructura , Conejos , Factores de TiempoRESUMEN
Experimental aortic intimal thickening has been induced in rabbits by sheathing the vessel with a polyethylene cuff. The alterations have been examined by light and transmission electron microscopy, during 12 months. An irregular intimal thickening develops as soon as the 15th day and includes numerous myofibroblasts with some other cells of monocytic or endothelial type. Microfibrils, elastic aggregates and collagen fibers are found in the intercellular space. Simultaneously, the media undergoes a fragmentation of the elastic laminae and the adventitia shows a capillary angiectasis and a granuloma. After 3 months there is, between the intimal smooth muscle cells, a progressive increase of elastic and collagenous material. In the media, elastic break up becomes more frequent after the 4th month and myocytes appear increasingly atrophic, which facilitates the extension of fibrosis. This is accompanied at times by a thinning of the arterial wall with or without localized disappearance of the media. All these modifications are discussed and compared to what we had previously found in the femoral artery [12].