Ultrastructural observations on different developmental stages of Goussia sinensis (Chen, 1955), a parasite of the silver carp (Hypophthalmichtys molitrix Valenciennes, 1844)
1989
Baska, F. | Molnar, K. (Hungarian Academy of Sciences Budapest (Hungary). Veterinary Medical Research Inst.)
The development of Goussia sinensis, a coccidium parasitizing the intestine of the silver carp /Hypophthalmichtys molitrix/ was studied by electron microscopy. All stages developed in the epithelial cells, less frequently in the goblet cells, and were located within a parasitophorous vacuole. In some cases one cell was invaded by several merozoites. 8-16 merozoites were formed within the meront by ectomerogony. The ultrastructural processes characteristic of gamogony were the same as those found for Goussia spp. parasitizing other fish species. A hitherto unknown mechanism of oocyst wall formation was observed. The oocyst membrane developing within the zygote surrounded only part of the zygote material, thus a small part of it left the oocyst proper. It is suggested that this zygote residue and the necrotic host cell constitute the so-called "yellow bodies" which includes the excreted oocyst. The oocyst wall was 40 to 60 nm thick. Oocyst sporulation took place within the fish. The sporocysts consisted of 2 hemispheres connected by sutures and had a 100-120 nm thick double wall. They were surrounded by sporocyst veils fixed to the oocyst wall by membranes.
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