THE MORPHOLOGY OF ELASTIN IN NONSPECIFIC AND INFLAMMATORY ABDOMINAL AORTIC-ANEURYSMS - A COMPARATIVE TRANSMISSION, SCANNING AND IMMUNOELECTRONMICROSCOPY STUDY

The maintenance of the mechanical properties of the vessels results fr om the correct arrangement of smooth muscle cells and extracellular fi brous proteins (elastin and collagen) in their wall. The morphology of extracellular matrix modifications, particularly of elastin, was inve stigated in inflammatory (IA) and non specific (NSA) abdominal aortic aneurysms by scanning (SEM), transmission (TEM) and immunoelectron mic roscopy. Both NSAs and IAs were significantly characterized by extensi ve extracellular matrix remodelling, including different patterns of e lastin degradation. Elastic and collagen fibres distribution appeared to be extensively altered in IAs, while it conformed more to a normal pattern in NSAs. With respect to NSAs, the morphology of elastic fibre s in IAs was modified to such an extent that their identification by T EM had a rely on immunocytochemical methods and by SEM on back-scatter ed electron analysis. The observed ultrastructural changes are indicat ive of the central role of extracellular matrix modifications in the p athogenesis of IAs and NSAs.