Ultrastructural aspects of fertile and sterile cysts of Echinococcus granulosus developed in hosts of different species

Bortoletti G. and Ferretti G. 1978. Ultrastructural aspects of fertile and sterile cysts of Echinococcus granulosus developed in hosts of different species. International Journal for Parasitology8: 421–431. Research was carried out on fertile and sterile cysts of Echinococcus granulosus taken from hosts of different species. Since the animals were bom and bred in Sardinia and had undergone spontaneous infection, this entails two reservations: firstly the stunted development of cysts in certain hosts, i.e. bovines, may be peculiar to a possible ‘Sardinian strain’ of E. granulosus; secondly, certain alterations in the germinal membrane may be due to parasite ageing. In some cases, the parasite may be dead despite the cyst appearing macroscopically normal because of the presence of the laminar layer.The germinal membrane ‘thrives’ to remarkably different degrees which do not, however, correlate with cyst fertility. The most thriving conditions are to be found in human cysts which are fertile; the germinal membrane may be thriving in pig cysts which are sterile; in sheep, the germinal membrane develops quite well and cysts are generally fertile; bovine cysts are generally sterile with stunted germinal membranes.There seems to be a direct correlation between cyst development and laminar layer thickness, whereas no correlations emerged with the organ in which cysts are located.