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Endocardial lesions in acute serum sickness in the rabbit. A scanning electron microscopic study
Abstract:
Endocardial lesions in acute serum sickness in rabbits were studied with the aid of scanning electron microscopy (SEM). Prominent inflammation developed most often in the ventricular (pocket) side of the mitral valve and was confined to a hollowed area formed between valvular ridges. The early lesion consisted of swelling of endothelial cells with monocytic attachments. Subsequently, frequent endothelial perforations occurred, through which a number of monocytes emigrated into the subendothelial space. Focal or diffuse endothelial desquamation then followed. SEM revealed that the denuded basement membrane also had many perforations enabling monocytic emigration into the deeper valve layer. The accumulated monocytes and proliferating mesenchymal cells produced a granulomatous focus in the valvular tissue in which some monocytes were observed to convert to Anitschkow cells. Infiltration by polymorphs was minimal. Deposition of fibrin occurred in the more severe valvulitic lesions, but no verrucous vegetation formation was observed. The inflammatory process regressed rapidly, leaving focal areas of fibrosis. A possible pathogenesis is discussed in connection with the pathophysiologic conditions of the mitral valve pocket.
Insights
Acute serum sickness causes endocardial lesions in rabbit mitral valves, characterized by endothelial cell swelling, perforation, and monocyte infiltration. Inflammation resolves, leaving fibrosis, with monocytes potentially transforming into Anitschkow cells.
Area of Science:
- Cardiovascular Pathology
- Immunology
- Electron Microscopy
Background:
- Acute serum sickness can induce inflammatory conditions affecting cardiac structures.
- The mitral valve's unique anatomy may predispose it to specific lesion development.
Purpose of the Study:
- To investigate the ultrastructural changes of endocardial lesions in rabbits with acute serum sickness.
- To elucidate the pathogenesis of mitral valve lesions using scanning electron microscopy.
Main Methods:
- Scanning electron microscopy (SEM) was employed to examine endocardial lesions.
- Rabbits with experimentally induced acute serum sickness were utilized.
Main Results:
- Lesions predominantly occurred on the ventricular side of the mitral valve.
- Early changes included endothelial cell swelling, monocytic attachment, and endothelial perforations.
- Monocytes emigrated into the subendothelial space, forming granulomas with potential Anitschkow cell conversion; fibrin deposition was noted in severe cases, but no vegetations formed.
Conclusions:
- SEM revealed a distinct pattern of mitral valve endocardial injury in acute serum sickness.
- Monocyte infiltration and transformation are key features of the inflammatory response.
- The lesions resolved rapidly, resulting in focal fibrosis.