Uniform strobilar development of Echinococcus multilocularis in vitro from protoscolex to immature stages.

The aim of this study was to obtain uniformity in strobilar development of Echinococcus multilocularis from protoscoleces in vitro. The isolate of E. multilocularis used was derived initially from a human case in France and subsequently maintained in the laboratory by intraperitoneal passage in Meriones unguiculatus. Protoscoleces used for culture were obtained using preparative procedures in which parasite tissue was disrupted gently with minimal exposure to pepsin and acidic conditions followed by immediate exposure to pancreatin in alkaline solution. Resultant cultures contained large numbers of evaginated, active, vermiform stages, which exhibited uniform strobilar development with formation of the first proglottid and segment and limited maturation of the first proglottid. All worms that exhibited proglottization subsequently segmented. Further proglottization did not occur and all worms degenerated within a few days following segmentation. The results are discussed in light of current knowledge of the relationships of somatic and germinal processes in Echinococcus. In view of these results, further studies should be encouraged to improve strobilar development of E. multilocularis in vitro.