Fasciola hepatica: early lesions in the viscera of seven pulmonate species after penetration of the miracidium.

Early lesions were studied in four viscera of seven pulmonate species on the 2nd day after miracidial exposure. The albumen gland, the digestive gland, and the gonad of infected snails demonstrated not only normal tissue but also the presence of two stages of epithelial necrosis. Multifocal necrosis predominated, with varying percentages of frequency depending on the snail species and stage of life; generalized necrosis was more seldom observed. In the kidney, epithelial necrosis was encountered more frequently than intralamellar deposits.