Fig. 1.

The oncosphere to metacestode metamorphosis in different tapeworms. A generalized summary of development is shown for different tapeworm groups. a Development in basal eucestodes, without the formation of an inner cavity. b Development in most cyclophyllidean tapeworms, with the formation of a cavity (primary lacuna, pl) during early development. The scolex invaginates or retracts into this cavity during later development. c Development in Echinococcus multilocularis. The tissues surrounding the primary lacuna expand into the thin germinal layer (gl), from which many brood capsules (bc) invaginate. The protoscoleces (ps) develop within the brood capsules, and are released when the metacestode is ingested by the definitive host. d Nuclear staining with 4’,6-diamidino-2-phenylindole (DAPI) of an E. multilocularis metacestode vesicle from in vitro culture, showing the continuity of the germinal layer (gl), brood capsule (bc) and protoscolex bud (ps bud). Bar: 20 μm