Morphological and ultrastructural changes in tissues of intermediate and definitive hosts infected by Protostrongylidae

Abstract

Cellular and subcellular mechanisms involved in tissue responses to larval and adult lungworms (Protostrongylidae) were respectively explored through experimental and natural infections in molluscan intermediate (Xeropicta candacharica) and ruminant definitive hosts (Ovis aries). Reaction to developing larval stages in the gastropod is manifested as cellular infiltration involving lymphocytes and macrophages into the infected tissue, which restricts damage and may result in destruction and elimination of parasites from the intermediate host. Variations in the patterns of localization for infective third-stage larvae in the foot tissue of the intermediate host are described. In the definitive host, evaluation of lung tissue by histology and transmission electron microscopy revealed the activation of lymphocytic and monocytic-macrophage systems. An intensive fibroblastic reaction in the lung parenchyma results in formation of connective-tissue capsules around helminths and more broadly demarcates zones of infected tissue. © TÜBİTAK.