ULTRASTRUCTURE AND HISTOCHEMISTRY OF THE TEGUMENT OF JUVENILE PARAMPHISTOMES DURING MIGRATION IN INDIAN RUMINANTS

The tegument of juvenile Paramphistomum epiclitum and Fischoederius el ongatus (Paramphistomidae: Digenea) resembles those of other digeneans . Seven types of papillae were observed, mostly on the oral and acetab ular surfaces, and increase in number during migration. Also evident a re two types of secretory body (T1 and T2) which are synthesized separ ately in tegumental cytons underlying the syncytium. Exocytosis of T2 bodies occurs at the apical membrane and appears to contribute to a fi brous glycocalyx. The tegumental syncytium lining the pharynx and acet abulum is thinner and has a higher capacity for vacuolation than the g eneral tegument. These may represent important sites for osmoregulatio n. The absence of mitochondria from the tegument in migrating juvenile s suggests limited involvement in energy demanding processes. Pigmenta tion of the subtegument is first evident in mature cercariae and is pr ogressively eliminated during migration.