Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 27. (Budapest, 1994)

the given organs. Therefore, for Sphaerospora-type myxosporeans organ specificity can be spoken of only in the phase of spore formation, when the site of dejection, the kidney, the ducts of sex organs and the gill epithelium can be indicated as locations. If we regard the blood path as an organ, the endothelium and the blood vessels can also be given as a location of the early Sphaerospora stages. Fig. 4. Sphaerospora-type development. The extrapiscine stage is followed by two intracellular stages, two blood stages and a coelozoic stage. (1) Extrapiscine development. (2) Actinosporeans floating in water. (3) Sporoplasms released from actinosporeans infect the epithelial cells of fish. (4) The trophozoites continue their development in the endothelial cells of capillaries. (5) In the parasite released from the endothelial cell a secondary cell develops by internal cleavage. (6) Division of the secondary cell gives rise to further cells. (7) In the secondary cells tertiary cells develop by internal cleavage. The majority of Sphaerospora species have a total of 8 secondary cells in one primary cell. (8) After disruption of the primary cell, the secondary cell and the tertiary cell contained by it may commence a new cycle of 8, but it also may start the second blood stage. (9) During the second blood stage numerous secondary cells are formed in the primary cell. (10) In the secondary cells usually two tertiary cells develop, which are identical with the future sporoblast. (11) After disruption of the primary cell the secondary cells get into the renal glomeruli and from there into the urinary passages. (12) In the urinary passages, the sporoblasts change into spores that leave the fish through the urinary bladder. (13) Spores.