Fine structure of Henneguya amazonica (Myxozoa) in ovarian follicles of Hoplosternum littorale (Teleostei) from the Amazon river.
During an ultrastructural study of oogenesis in Hoplosternum littorale collected from the lower Amazon river near Belem, Brazil, from March to May 1993, Henneguya amazonica was observed inside the follicles and ovarian stroma. The presence of myxosporeans in sexual tissues of teleosts is rather unusual and has previously been described only for this group of fishes. The parasite formed cysts between the zona pellucida and follicle cells of the oocytes. Inside these cysts were found early phases of sporogenesis. In the ovarian stroma only mature spores were found; no cysts were seen. An ultrastructural description of the early sporogenic phases of the parasite is presented. The possible infection cycle and implications for the reproductive potential of the host are briefly discussed.