Cellular reactions in tongue and gut in murine trichinellosis and their thymus-dependence

Summary Histological changes in gut, tongue and three lymphoid tissues (spleen, mesenteric and mandibular lymph nodes) which occurred after oral infection of both thymus-bearing and congenitally athymic mice with the nematode Trichinella spiralis were studied by light microscopy for 42 days. The basophilic transformation and the enzyme cytochemical changes of tongue muscle fibers in connection with the larval encystation occurred in both groups of animals and was thus thymus-independent. A cellular inflammatory reaction including eosinophils, mononuclear cells and mast cells in the parasitized tongue occurred in both groups, albeit to a lesser extent in the athymic animals. The kinetics of this cellular response were the same in both groups. Eosinophilia in the gut was observed in thymus-bearing mice only during the early phase of infection and in athymic mice in the latter part of the observation period, suggesting a partial thymus-independence of the phenomenon. Typical immunohistological changes in the lymphoid tissues and antibody production occurred only in the thymus-bearing animals. The cellular reactions in the parasitized gut and tongue can only partially be explained by a delayed hypersensitivity aetiology.