Ultrastructural observations on merogonic and gamogonic stages of Goussia carpelli (Apicomplexa, Coccidia) in experimentally infected common carp Cyprinus carpio

Abstract

Ultrastructural features of merogonic and gamogonic stages of Goussia carpelli, a coccidian parasite of carp are described. The parasite developed along lines often found in eimerian parasites in the apical portion of intestinal epithelial cells. After laboratory infection, merogonic stages were found at days 2 to 7 post exposure (PE). Meronts gave rise to 12 to 20 merozoites by endomerogony. Gamogonic stages occurred between days 7 and 9 PE. Young macrögamonts developed in parasitophorous vacuoles with narrow spaces. Differentiations of the macrogamont's surface or the parasitophorous vacuole membrane that could be regarded as "feeding organelles" were not observed. Young oocysts were surrounded by an envelope composed of three layers and contained large clusters of electron dense material.