Resumen de The morphology of sporocysts of eurytrema coelomaticum (trematoda, dicrocoeliidae)
Jairo Pinheiro, Daniele O. Franco Acuña, Solange V.P.B. Brandolini, Aleksandra Oliveira Menezes, Wanderley de Souza, Renato A DaMatta
Eurytrema coelomaticum is a fluke that infects ruminants in South America, Europe and Asia. The morphology of the mother and daughter sporocysts of E. coelomaticum obtained from Bradybaena similaris, the first intermediate host, is described for the first time by light and scanning electron microscopy. The intermediate host was exposed to E. coelomaticum eggs and after 30 days the mother sporocyst was found in the coelom adhered to the intestine wall. This sporocyst was a rounded or elongated mass (0.1078mm), with numerous germinal balls in it, and a folded tegument with no specializations. The daughter sporocysts obtained following dissection of infected snails have varied shape, one hollow tapered region with many transversal and longitudinal striations, named anterior end. The expelled daughter sporocyst presented an oval sac-like central region with a small anterior and a posterior longer filament-like prolongation. The measures of the expelled sporocysts are presented and compared to previous descriptions. The mother sporocyst was attached to the coelome of the intestine wall of intermediate snail host B. similaris, intimately adhered in some regions. It presents a highly folded tegument with granules and the body wall was composed by an outer syncitial layer, basal lamina, and circular and longitudinal muscle layer. Below was the cell body (cyton) with the nucleus. The daughter sporocysts obtained by dissection exhibited many granules and secretory vesicle in the outer layer indicating an intense secretory activity. The body wall presented the same layers of the mother sporocysts, but the outer syncitial layer invaginated and an amorphous layer was present between the syncitial and circular muscle layers. The protonephridial excretory system was viewed. The anterior and posterior end of the expelled sporocyst exhibit a degenerated structure, but biological activity still occurred in these regions. The swollen middle of the body was filled by a lamellar structure formed by degenerating membranes, but the excretory system was preserved. The endocyst wall was fibrilar and filled by cercariae and amorphous, membranous and secretory material inside it. By the first time, the morphology of E. coelomaticum sporocysts was deeply analyzed using different microscopic techniques, elucidating points of their structure, being an important tool to the taxonomy of this species of trematode.
