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The pathological effects of Bothriocephalus acheilognathi on the gut of experimentally infected carp, Cyprinus carpio L. have been studied. Light and electron micro- scopical observations revealed that damage to the host gut was not restricted to the area engulfed by the bothria, and loss of gut microvilli and the separation and shedding of enterocytes occurred against the site of attachment. Lymphocytes, macrophages and eosinophils accumulated in the wall of the infected gut and migrated into the lumen where they adhered to the parasite tegument. The role of parasite-derived and host-produced factors in leucocyte migration and attachment to the worm are discussed. [ABSTRACT FROM AUTHOR]

The cellular response, within the kidney of experimentally infected carp to the presence of eggs of the blood fluke Sanguinicola inermis has been investigated using transmission electron microscopy. Initially, 0-1-week-old eggs were surrounded by host eosinophils which degranulated and broke down adjacent to the egg shell. Infiltration by neutrophils and monocytes occurred around 1-2-Week-old eggs. Eggs at 2-3 weeks of age began to become encapsulated, although the first signs of structural damage appeared when the eggs were 5-6 weeks of age. [ABSTRACT FROM AUTHOR]

This article presents a study related to Ligula intestinalis. The usual site of infection and development of the plerocercoid of Ligula intestinalis is in the body eavity of the host fish. In roach, Rutiliis mtiliis, multiple infections and extensive growth of the parasite leads to gross distension of the ventral body wall. Researchers report an unusual intramuscular site of infection observed in roach fry and describe the interaction of the plerocercoid with the host muscle and leucocyte response.

Infections of roach, Rutilus raillus L., with the plerocercoid larva of Ligula intestinal/s result in a pronounced host cellular response which consists of a leucocyte and connective tissue component. Using ultra structural, histochemical and tracer techniques, three Leucocyte cell types (L1. L2 and L3) have been observed. L1 cells, the most numerous cell type, pass through a number of characteristic developmental stages. Phagocytosis occurs in stages 1, 2 and 3. Stages 1 and 2 contain predominantly primary lysosomes and secondary lysosomes respectively, and in cells of stage 3 residual bodies are found which may be released following disruption of the cell at stage 4. The lysosomes and residual bodies do not contain acid phosphatase although arylsuiphatase activity is present in all secondary lysosomes and residual bodies and in a few primary lysosomes. L1 cells are thought to be macrophages. L2 and L3 cells are relatively rare. The former contain granules resembling those found in mammal- ian cosinophils but which themselves are not eosinophilic or acid phosphatase and arylsulphatase positive. L2 cells are phagocytic and are thought to be neutrophils. L3 cells are also phagocytic and may represent rnacrophage precursors. Despite the presence of a host cellular response parasites survive apparently unharmed as long as the host lives. The significance of this is discussed. [ABSTRACT FROM AUTHOR]