[Pathomorphological changes after the single aerosol vaccination of broilers against Newcastle disease]

Morphologic studies were carried out with broilers at the age of 27 days after the single aerosol treatment with the B1 vaccine against Newcastle disease. Investigated were the lungs, liver, spleen, and the bursa of Fabricius. It was found that the proliferation response of the reticulo-endothelial system set in as early as the third days following vaccination, its manifestation being most strong in the lungs. The activation of the reticulo-endothelial system reached its peak on the 15 th to 18 th day, after which it progressively declined. On the 30 th day following vaccination there were still traces of the proliferative reaction in the bursa and the spleen. No serious destruction was noted in the lungs with the exception of epithelial desquamation in the bronchioles.