Pathogenesis of Lesions of the Autonomic Nervous System of the Mouse in Experimental Acute Chagas' Disease

Light and Electron Microscope Studies

W. L. TafuriDepartamento de Patologia and the Centro de Microscopia Eletrônica, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil

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After standardizing a technique for isolation of the subepicardiac ganglia, the pathogenesis of lesions of the autonomic nervous system of the mouse caused by Trypanosoma cruzi was studied by optical and electron microscopy. Nine albino mice, inoculated with T. cruzi and killed after 6, 9, 12, and 15 days, were used. The following alterations were observed: 1) frequent parasitism of the capsular fibroblasts, Schwann cells, and satellite cells; 2) the living normal parasites cause the formation of a vacuole in the host cell, without any alteration of the surrounding tissues; 3) when the parasite or host cell, or both, degenerate, a local acute inflammation appears (periganglionitis and ganglionitis) that injures the neighboring structures (neurons and nerve fibers); 4) the parasitism is randomly distributed throughout the nervous system, thus explaining why the lesions occur in irregular foci of unpredictable localization; and 5) there is no selectivity of the autonomic nervous system by T. cruzi. Analysis of the results demonstrated that the pathogenic mechanisms responsible for the lesions of the autonomic nervous system of the heart are multiple, all contributing to the same end result: denervation of the organ, already demonstrated by optical microscopy.