COMPARISON OF ECHINOSTOMA-CAPRONI MOTHER SPOROCYST DEVELOPMENT IN-VIVO AND IN-VITRO USING BIOMPHALARIA-GLABRATA SNAILS AND A BIOMPHALARIA-GLABRATA EMBRYONIC-CELL LINE

Biomphalaria glabrata embryonic (Bge) cells have previously been shown to permit a successful cocultivation of Schistosoma mansoni and Schis tosoma japonicum from miracidia to mother sporocysts (MS) and then to the production of daughter sporocysts (DS). To investigate further the properties of the Bge culturing system we used Echinostoma caproni un der identical in vitro conditions. In vitro-derived miracidia were use d either for experimental infections of B. glabrata snails, or for in vitro cultivation with Bge cells. Histological analysis showed that th e development of MS in B. glabrata was similar to the previously descr ibed development in Biomphalaria pfeifferi in terms of final site of i nfection, development dynamics, growth dynamics, reproduction intensit y, and life spans. Only short delays in migration dynamics were observ ed in B. glabrata. When cultivated under in vitro conditions, E. capro ni MS could live for up to 17 wk in the presence of Bge cells, as comp ared with 2 wk in cell-free Bge medium. The presence of Bge cells also permitted significant growth of MS and development through complete e mbryogenesis of the next intramolluscan stage (embryos of 100-110 cell s). However, degeneration of MS consistently occurred before productio n of this second generation. During the entire cultivation period, no visible contact was observed between MS and Bge cells, suggesting that development of MS was only triggered by soluble factors released by B ge cells.