Gorgoderina vitelliloba: interaction with frog leucocytes in vivo and in vitro

Ultrastructural observations were made on the response in vivo of adult Rana temporaria to Gorgoderina vitelliloba and the interaction between host cells and the parasite in vitro. In both cases, the cellular attack on the fluke was most intense 21-23 days postinfection. Host leucocytes (believed to be eosinophils) lay flat against the surface of the parasite. Degranulation of their electron-dense, peroxidase-positive granules occurred and vacuoles formed. The outer plasmalemma of the tegument was breached and eosinophils migrated over the basal lamina, stripping the tegument from the surface of the fluke. The cellular response was so vigorous in vitro that the tegument was sometimes completely lost. In vivo, damage was slight, and the majority of the parasites successfully completed their migration to the bladder, where there was no further cellular response, and tegumental repair occurred. The fact that the migration of the fluke from the kidney to the bladder occurred at the same time as the peak of the cellular response may not be coincidental, and it is suggested that the cellular attack may initiate migration from the kidneys.