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 (Poly opisthocotylea), a gill parasite from Diplodus argenteus (Valenciennes , 1830), is composed of ''U''-shape hematin cells and a connecting syn cytium, both having cytoplasmic lamellae. These cells show outgrowths and bent folds which were seen to enclose lumen material. The trapped material was then subjected to endocytosis. The nature of ingested foo d material was comparatively analyzed by cytochemical and histochemica l tests. Blood residues were detected in the gut but tests for mucins were negative. No intact erythrocytes were observed in the gut lumen.