Studies on the Life History of Eurytrema pancreaticum Janson, 1889

Abstract

The trematode is common in the pancreatic and biliary passages of cattle and other herbivorous mammals in the Orient. The intermediate hosts are 2 land snails of the family Fruticoidolidae, Bradybaena similaris and Cathaica ravida sieboldtiana. The structure of the egg and miracidium was very similar to these stages descr. for several other Dicrocoeliinae. The eggs hatch only after being eaten by the snails, and the mother sporocyst develops in the digestive gland, closely surrounded by the host''s tissue. The mother sporocyst becomes a large, rather irregular lobed structure. In its early development there is an extensive multiplication of germinal cells like that descr. for Dicrocoelium dendriticum and certain plagiorchiids. The daughter sporocysts develop, within the matrix of the mother, into large complicated sacs with heavy walls which escape from the snails. The cercaria has a short, stumpy tail and the structure of its body is very similar to that of the other dicrocoeliid cercariae. Since attempts to infect goats with the free daughter sporocysts were not successful it is not known whether or not a 2d intermediate host is required. While the structure of the larval stages shows that the Dicrocoeliinae are closely related to the Plagiorchiidae, their life cycles show a number of striking differences from those of the latter group which are evidently modifications for transmission by land snails.