The ultrastructure of the gastrodermis and the nutrition of the gill parasitic Atriaster heterodus Lebedev and Paruchin, 1969 (Platyhelminthes: Monogenea).

The gastrodermis of Atriaster heterodus Lebedev & Paruchin, 1969 (Polyopisthocotylea), a gill parasite from Diplodus argenteus (Valenciennes, 1930), is composed of "U"-shape hematin cells and a connecting syncytium, both having cytoplasmic lamellae. These cells show outgrowths and bent folds which were sent to enclose lumen material. The trapped material was then subjected to endocytosis. The nature of ingested food material was comparatively analyzed by cytochemical and histochemical test. Blood residue were detected in the gut but tests for mucins were negative. No intact erythrocytes were observed in the gut lumen.