Parasite Of Carp Research Articles

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

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.

Light and electron microscopic observations on the swimbladder stages ofSphaerospora renicola, a parasite of carp (Cyprinus carpio)

The developmental cycle of stages of Sphaerospora renicola, proliferating in the walls of the swimbladder in carp fry and responsible for swimbladder inflammation (= SBI stages) is described. The initial stage, a primary cell containing two secondary cells, grows in size while the secondary cells divide and produce two tertiary cells each by endogenous division. After a supposed disintegration of the grown primary cell, the cell triplets are released to repeat the cycle. The cell divisions are asynchronous and the development of the whole formation may be quite irregular. The cytology of these stages is closely reminiscent of the blood stages of S. renicola and also shares common features with the parasite's sporogonic stages. The SBI stages show typical features of myxosporean organisation, i.e., a "cell-within-cell" arrangement in which the primary cell contains secondary cell(s) in membrane-bound vacuoles and many free ribosomes, in the absence of centrioles. Other salient features of SBI stages are partitions in the nuclei; a small amount of cytoplasm in the early secondary cells; distinct, age-dependent changes in morphology of the nucleus; and atypically shaped Golgi bodies in the cytoplasm or integrated with the nuclear envelope. The cytological features and significance of swimbladder stages are discussed in detail.