Cell composition of the head kidney of European chub (Squalius cephalus L. )

The aim of the present study was to perform quantitative and qualitative evaluations of developing blood cells in the head kidney of European chub, Squalius cephalus (L.). Twenty-one types of hematopoietic precursors and mature cells were identified in head kidneys isolated from ten juvenile fish. The lymphoid lineage was the most abundant, followed by granuloid, erythroid, thrombocytoid, blast, and monocytoid cells. The lymphocyte was the most frequently occurring cell in the kidney and the most numerous of the lymphoid cells. The neutrophilic lineage was the most numerous among the granuloid cells. The erythropoietic series comprised five stages (erythroblasts: basophilic, polychromatic, orthochromatic; young and mature erythrocytes), more than the numbers of developmental stages of any other lineages. Juvenile cells were more abundant than mature stages in the head kidney. Only mature eosinophils and thrombocytes were found in chub hematopoietic tissue. The cellular composition in chub hematopoietic tissue was similar to that in other fish species.