Endocardial lesions in acute serum sickness in the rabbit. A scanning electron microscopic study.
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.
D000818:Animals; D001485:Basement Membrane / Q000648:ultrastructure; D004696:Endocarditis / Q000473:pathology; D004699:Endocardium / Q000648:ultrastructure*; D004727:Endothelium / Q000648:ultrastructure; D005337:Fibrin / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D008943:Mitral Valve / Q000648:ultrastructure; D009000:Monocytes / Q000648:ultrastructure; D011817:Rabbits; D012713:Serum Sickness / Q000473:pathology*
D005337:Fibrin