[The tegument of Euzetrema knoepffleri, endoparasitic Monogenean of an amphibian: ultrastructure and evolution during the life cycle (author's transl)].

Euzetrema knoepffleri is an endoparasitic monogenean from the bladder of an Amphibian. Ultrastructural studies of the integument are made during the three stages of the life cycle: oncomiracidium, renal post-larva and adult. The meaning of the structures is discussed during the larval evolution to the adult and is compared with that of other monogeneans. The transition from fresh water to an urinary environment is in relation with the folding of the internal cytoplasmic membrane. This adaptation is specialized in water and ion transport through the integument, necessary for for the osmotic readjustment of the parasite: It has been noted that the tegument integrates ultrastructural adaptations to the biotope, independent of the phylogeny.