Light and electron microscopic studies on various developmental stages of Hoferellus cyprini (Doflein, 1898)

The development of Hoferellus cyprini (Myxosporea) in common carp was studied by light and electron microscopy. It has been established that in the autumn the early developmental stages are located in a cell syncytium formed from the epithelium of the renal tubules. The authors share the opinion of Lom and Dyková [13] that each intracellular trophozoite corresponds to a primary parasitic cell which contains secondary, tertiary and quaternary cells having formed by internal cleavage. From December the trophozoites are released into the tubular lumen, and the secondary cells are transformed into coelozoic plasmodia. Spores are formed inside the Plasmodia in the ureter or renal tubules in April. The sporoblast cells correspond to the quaternary cells of the trophozoites. On the surface of each of the two spore valves 10 striations run longitudionally and continue in bristles at the caudal end of the spores. Morphologically, the spores are consistent with the description of Mitraspora cyprini Fujita, 1912. Therefore, the authors regard M. cyprini as a synonym of Hoferellus cyprini (Doflein, 1898).