Fasciola hepatica : in vitro production of daughter rediae and cercariae from first- and second-generation rediae

Abstract

Fasciola hepatica mother rediae belonging to the first generation and the first cohort of the second generation were extracted from their snail intermediate host (Lymnaea truncatula) and maintained in vitro for 16 days to determine the quantity of daughter rediae and cercariae produced by each generation. L-15 Leibovitz medium with a saline fraction adjusted to that of the L.␣truncatula hemolymph was used for experiments. A total of 35 daughter rediae exited from the 21 mother rediae of the first and second generations, which were 14–32 days old at the onset of culture. Microscope examination of the mother rediae demonstrated the presence of numerous redial embryos and differentiating daughter rediae, whereas no cercaria was seen within their body. A total of 49 cercariae exited from the 17 mother rediae of the first and second generations, which were 29–50 days old at the onset of culture. No differentiating daughter redia was seen in these last mother rediae. The productivity of the first or second generation (first cohort) was nearly identical in terms of cercariae.