Development of haemogregarines (Apicomplexa), blood parasites of eel, Anguilla anguilla (L.)

Abstract

Haemogregarines were found in 23 (2.8%) out of 820 eel, Anguilla anguilla (L.) individuals caught in the Szczecin Lagoon and lakes D±bie, Siecino, Drawsko, and Lipiany (north-western Poland). Different developmental stages were present predominantly in the leukocytes and extracellularly; more seldom, they occurred also in the peripheral blood erythrocytes, in the liver, spleen, and kidney. Merogony involving different stages with nuclear chromatin aggregated into 2, 4, 8, 16, 32 and more groups within a cell was followed. During the subsequent differentiation, chromatin shifted to the cell periphery and merozoites (up to 32 and more), attached to the residual body, were formed by separation. The released merozoites were scattered between cells. During gamogony, gamont-resembling forms were formed as a stage terminating development in the fish host.