Ultrastructure of excretory system ofTrilocularia acanthiaevulgaris (Cestoda,Tetraphyllidea)

The fine structure of the excretory system in the juvenile (plerocercoid-like) form ofTrilocularia acanthiaevulgaris is described. The flame cell bears a bunch of 50–70 cilia, which are anchored in the cytoplasm by means of basal bodies possessing striated rootlets. All the cilia in the flame are aligned in the same direction. The flame and duct cells are connected by interdigitating ribs of cytoplasm separated by a fibrous sheet. Both internal and external leptotriches are also present. The lumen of the excretory ducts is intracellular in origin. The apical surface of the cytoplasm lining the duct is convoluted and its surface area is further amplified by means of microvilli. The fine structure of the excretory system in this primitive tapeworm is compared with that described for other parasitic and free-living flatworms.