Description of Eggs and Larval Stages of Fasciola , Light and Scanning Electron Microscopic Studies

摘要

Light Microscopy (LM) and Scanning Electron Microscopy (SEM) were used to study the egg and miracidium of Fasciola gigantica and redia, cercaria and metacercaria from field infected Lymnaea (cailliaudi) natalensis snails, to analyze the differences between eggs and intra-molluscan stages of F. hepatica and F. gigantica in a zone of sympatry. The egg of F. gigantica has an umbilicus-like invagination at the posterior end of the egg shell. The emerged miracidium has an elongated conical body that has a broad anterior end and tapering posterior end. The surface was found to be covered with varied lengths of cilia except regions of lateral connection of epidermal plates. The redia of Fasciola sp. has a caudal papilliform process. Tail of cercaria was found to be provided with two fin folds. Steps of encystation of the cercaria were described as a variable morphological change in cercarial body and cyst wall.