Ultrastructural recognition of dendritic cells in the intimal lesions of aortas of chickens affected with Marek's disease

The present study was undertaken to determine whether dendritic cells contr ibuted to the intimal abnormalities seen in the aortas of chickens infected with Marek's disease. Semithin sections were used to select aortic segment s in which the intima was thickened by lymphocytic infiltrates. Ultrathin s ections were then examined. Intermingled with lymphocytes within the intima l thickenings were cells with an appearance typical of dendritic cells incl uding long processes and a unique tubulovesicular system. In these cellular processes the tubulovesicular system was hypertrophied with the tubular ci sterns characteristically forming concentric cyclical layers. Our observati ons show that dendritic cells are present in the aortic lesions of Marek's disease and are presumably involved in related immune mechanisms.