Blood cells of sea bass (Dicentrarchus labrax L.). Flow cytometric and microscopic studies

Studies of fish blood cells made to date presented numerous problems derive d from both the nomenclature and the techniques used. A combination of quan titative and morphological methods is needed if the classification of fish blood cells is to advance from it present provisional state. The aim of the present paper was first to isolate sea bass blood cell populations by flow cytometry and second to characterize then microscopically. Blood cell popu lations from sea bass (Dicentrarchus labrax L.) were isolated according to their FSC (size) and SSC (granularity) properties by flow cytometry. The is olated populations were then processed for light and transmission and scann ing electron microscopic characterization. Sea bass blood leukocytes isolat ed by flow cytometry consisted of two main cell subpopulations. Subsequent microscopic study of these cells revealed that the first subpopulation was composed of small cells (3-5 mu m) of low granularity and consisted of thro mbocytes and lymphocytes whereas, the second subpopulation was formed of 6- 9 mu m sized cells of high granularity consisting of granulocytes and monoc yte/macrophages. The combined use of flow cytometry and electron microscopy makes it possible to characterize the different cell types present in sea bass peripheral blood with a high degree of certainty. Although sea bass ba sically follows the common vertebrate hematological pattern, significant mo difications such as the presence of circulating immature erythrocytes, plas ma cells and monocyte/macrophages and different forms of thrombocytes can b e established with respect to this pattern. Anat Rec 258:80-89, 2000. (C) 2 000 Wiley-Liss, Inc.