ORGAN DISTRIBUTION OF CARP (CYPRINUS-CARPIO) LEUKOCYTES DURING ONTOGENY

Organ distribution of leucocyte subpopulations was examined in carp (C yprinus carpio) development by flow cytometric analysis using monoclon al antibodies raised against: carp immunoglobulins, early thymocytes, thrombocytes, and monocytes/macrophages. In thymus, a high percentage of early thymocytes was found. In head kidney, Ig-bearing cells first appeared more numerous than in other organs. In spleen only early thym ocytes and thrombocytes are relevant. In gut, early thymocytes are det ected in the first week, but they significantly decrease during ontoge ny. The percentage of Ig-bearing cells remains low throughout developm ent. In peripheral blood leucocytes of 1-week-old carp, early T cells are the only detectable leucocyte subpopulation. From 7 days onwards, the percentage of monocyte/macrophages increased; thereafter, thromboc ytes and B cells became detectable. This study provides new indication s on the major sites of lymphopoiesis and thrombopoiesis in carp.