The host-parasite interface and associated structures of the cercaria and adultNeophasis lageniformis(Lebour, 1910)

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Abstract
Tail-bearing and tailless intraredial cercariae of Neophasis lageniformis were studied in the transmission and stereoscan electron microscopes, and the adult stages were studied in the stereoscan electron microscope. All developmental stages are provided with flattened, serrated spines which gradually diminish in size towards the posterior end. They also possess a few sensory structures, composed of an apical cilium and a bulbous base in connection with nerve tissue. Only one cell type, the tegumentary cells of previous authors, connects with the syncytial tegument. Vesicles synthetized in the tegumentary cells enter the tegument through the cytoplasmic connections. In the tegument the most apically located vesicles apparently release their contents into the surrounding medium. Several layers of muscle fibres rich in beta glycogen particles are found below the basal lamina of the tegument. In young tail-bearing cercariae processes of supposed parenchymal cells look nearly empty, whereas in tailless stages they are rich in alpha glycogen particles. The morphological observations are discussed in relation to the biology of the different developmental stages of the trematode.