The respiratory tract in pigs and its immune system: a review.

The growing amount of information regarding mucosal immunology in animals resulted from a need to better understand the pathogenesis of diseases entering the body through mucosa surfaces, including the respiratory tract. The second reason for such studies is associated with a search for alternative ways of vac - cine application, including delivery to the mucosa of the respiratory tract. This review provides a structural and functional description of the immune system of the pig respiratory tract.