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      Métodos de Impregnación Metálica para el Estudio de las Fibras Reticulares Miocárdicas: Estudio comparativo

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          Abstract

          La observación y evaluación de la MEC reticular en los cortes de miocardio facilita la interpretación de los procesos patológicos como: hipertrofia y atrofia celular, necrosis, engrosamiento de las membranas basales vasculares y engrosamiento y desorganización del endomisio y perimisio. Se compararon los cortes de 10 casos con enfermedades cardiovasculares teñidos con cuatro métodos de impregnación metálica para la visualización de fibras reticulares de la MEC. De los métodos empleados (Gridley, Gomori, Snook y Wilder) se consideró que el de Gomori ofreció mayor grado (IV) de optimización (3/8) para la visualización de los elementos tisulares evaluados (perimisio, endomisio, membrana nuclear y basal).

          Translated abstract

          The valorarion of the reticular extracellular matriz (ECM) in the myocardial sections is usefull in order to interpretate certain pathologic proceses such as: cell hypertrophy and atrophy, necrosis, thickness of vascular basement membrane and tickness and disorganization of the endomysium and perimysium. Sections of 10 cardiovascular disease cases were compared using four methods of metal impregnation to visualize reticular fibers in the ECM. Of the four methods used (Gridley, Gomori, Snook and Wilder) the Gomori method offered a highest level of optimization (3/8) to visualize the histological elements evaluated (perimysium, endomysium, nuclear and basement membrane).

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          Most cited references13

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          Patterns of myocardial fibrosis in idiopathic cardiomyopathies and chronic Chagasic cardiopathy.

          A. Rossi (1991)
          To study the fibrillar nature and structural features of the collagenous interstitium of the myocardium in normal and cardiomyopathic human hearts, employing the picrosirius red technique and polarization microscopy. A survey, case series study. Referral autopsy service at a university medical centre (Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto). A total of 46 adult hearts obtained at autopsy were used: five control hearts without evidence of cardiac disease, nine hearts with dilated cardiomyopathy, five with hypertrophic cardiomyopathy, four with endomyocardial fibrosis affecting the left ventricle, and 23 with chronic Chagasic cardiopathy. Fragments of myocardial tissue were obtained from the equator of the left ventricular free wall, fixed in formalin, dehydrated, and embedded in paraffin. Sections were stained with a modification of the picrosirius red technique and examined using direct light and polarization microscopy. The findings in the control myocardium did not differ from those reported in the literature. The myocardium in both dilated and hypertrophic cardiomyopathies showed diffuse fibrosis varying in degree from one case to another, but present in all cases. The basic pattern was characterized by a diffuse increase in both endomysial and perimysial collagen thick fibres, particularly surrounding individual myocytes (endomysial sheath). The microscopic study of the cases of endomyocardial fibrosis showed a thickened fibrotic endocardium consisting predominantly of thick collagen fibres extending as a septum, corresponding to broad perimysial sheaths, into the myocardium. In the superficial muscle fibre bundles usually composed of atrophic fibres, there was an increase in thickness of collagen fibres in both the perimysial and endomysial connective tissue matrix. To a variable degree (but present in all cases) interstitial and diffuse fibrosis could be observed in the chronic myocarditis of Chagas's disease. This was manifested by a diffuse increase in the amount of thick collagen fibres surrounding muscle fibre bundles (perimysial matrix), varying in intensity from one area to another, and around intramural coronary vessels, combined with a less pronounced increase in the endomysial collagen matrix. These findings extend knowledge of the various expressions of interstitial myocardial fibrosis in the idiopathic cardiomyopathies and chronic Chagasic cardiopathy and perhaps provide insight into pathogenesis. Further research into the patterns and pathogenesis of myocardial fibrosis are needed in order to offer prevention and corrective forms of therapy of the fibrotic process.
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            Specific alterations in the distribution of extracellular matrix components within rat myocardium during the development of pressure overload.

            Cardiac hypertrophy secondary to a sudden aortic pressure overload results in the remodeling of myocytes and extracellular matrix components. Hydroxyproline quantitation to evaluate total collagen content and immunocytochemistry procedures were used to analyze the temporal appearance and regional distribution of collagen, laminin, and fibronectin during the early stages of pressure overload. The study was performed in 25-day-old rats submitted to a thoracic aortic stenosis and killed from 1 day to 18 days after surgery. Cardiac hypertrophy reached 24.5% by day 2 and 75.5% by day 15. Each extracellular matrix component showed a unique distribution throughout the myocardium: in normal hearts, type I/III collagens appeared mainly as large strands or waves around groups of myocytes, fibronectin predominated around small and large vessels, while laminin surrounded both myocytes and capillaries. As early as 2 days after surgery, fibronectin and type I/III collagens, but not laminin, accumulated in focal areas. Thereafter, these areas increased in size and number within the inner part of the left ventricle, and progressively affected the whole left ventricle. Fibronectin accumulation preceded that of collagen and occupied larger areas. The measure of hydroxyproline content demonstrated that during the 1st week after surgery the increase in collagen content is correlated with the increase in heart weight. In conclusion, the three components of the extracellular matrix studied here develop a specific pattern of accumulation in response to a sudden pressure overload that induces cardiac hypertrophy. Both fibronectin and collagen changes participate in the healing of focal myocardial necrosis secondary to the increased hemodynamic work and fibronectin appeared as a more sensitive marker of the cardiac lesions than collagen.
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              Myocardial fibrosis in nonhuman primate with pressure overload hypertrophy.

              Characteristics of pressure overload hypertrophy are known to include an accumulation of collagen (or fibrosis) and a biochemical remodeling of fibrillar type I and III collagens. The corresponding structural nature of myocardial fibrosis is less clear. This light morphologic study was undertaken to address this issue in the hypertrophied left ventricle of the nonhuman primate with experimental hypertension. For this purpose, the picrosirius red technique and polarization microscopy were used to examine the myocardium during the evolutionary, early, and late phases of established hypertrophy corresponding to 4, 35, and 88 weeks of experimental hypertension. Evidence of increased thin perimysial fiber formation, together with collagen fiber disruption and edema at 4 weeks of hypertrophy, was found when the chamber volume to left ventricular mass ratio was reduced. After 35 weeks, when this ratio was again normal, a greater number of intermuscular spaces contained both thick and thin perimysial fibers. In addition to this interstitial fibrosis, a reactive fibrosis consisting of a meshwork of thick and thin perimysial fibers was seen extending over muscle fibers. Finally, at 88 weeks, this fibrous meshwork had encircled muscle and there now was evidence of cell necrosis. The accompanying replacement fibrosis consisted of yet another distinctive orthogonal grid of thick and thin collagen fibers. Thus, a continuum of fibrillar collagen remodeling was seen in pressure overload hypertrophy in the nonhuman primate myocardium. Structurally distinct patterns of myocardial fibrosis were recognized based on the alignment of perimysial fibers with muscle that may explain the cellular remodeling and altered mechanical behavior of the concentrically hypertrophied myocardium.
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                Author and article information

                Journal
                rfm
                Revista de la Facultad de Medicina
                RFM
                Universidad Central de Venezuela. Facultad de Medicina. Comisión de Publicaciones de la Facultad de Medicina (Caracas, Distrito Capital, Venezuela )
                0798-0469
                December 2002
                : 25
                : 2
                : 224-230
                Affiliations
                [01] orgnameUCV orgdiv1Instituto Anatomopatologico Jose A. O´Daly orgdiv2Laboratorio de la Seccion de Patologia Cardiovascular
                [02] orgnameUCV orgdiv1Instituto Anatomopatologico Jose A. O´Daly orgdiv2Seccion de Patologia Cardiovascular
                Article
                S0798-04692002000200011 S0798-0469(02)02500211
                221411d9-405c-45a2-a06a-5cf0441d77d0

                http://creativecommons.org/licenses/by/4.0/

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                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 13, Pages: 7
                Product

                SciELO Venezuela

                Categories
                Trabajos Originales

                Histological methods of metal impreganation,Reticular extracellular matrix,Reticular fibers,Métodos de impregnación metálica histológica,Matriz extracelular reticular,Fibras reticulares

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