Further Studies on the Pathogenesis of the Ascaridic Granuloma

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  • Department of Pathology, College of Medicine, University of Florida, Gainesville, Florida
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Injection of heat-killed Ascaris eggs into the subcutaneous tissue, skeletal muscle and peritoneal cavity of rats and into the liver of rabbits results in an inflammatory reaction identical to that following the injection of live eggs. This suggests that the metabolic products of the live embryo play little or not role in the genesis of the inflammatory reaction.

The removal of the chitinous layer by chemical means does not alter the type or evolution of the inflammatory lesions, except for a less marked eosinophilic response.

The more intense inflammatory response in the immune animals within 24 hours after inoculation as well as the presence of fibrinoid necrosis in pseudotubercles, the faster resorption of injected eggs and the more rapid healing of the lesions in comparison with the controls, suggests an immunological process in the pathogenesis of these lesions.

The absence of histologic alterations following the injection of lipids extracted from Ascaris eggs in easily resorbable suspension and the similarity of the inflammatory process subsequent to the injection of either whole, decorticated or lipid-free eggs and of lipids in poorly resorbable form indicate that the granulomatous inflammation is chiefly an unspecific response from the tissues of the host against the foreign material injected.