Abstract
The characterization of rainbow trout peripheral blood leucocytes (PBL) was carried out by flow cytometry (FCM) analysis and by transmission electron microscopy. Two major cell populations were identified in FCM analysis. One population showed small values in both forward scatter (FS) and side scatter (SS), and the other population showed large values in both parameters. These major populations were divided into two sub-regions each (A/B and C/D). There was no significant difference in cell populations between sub-regions A and B. However, a difference was observed in the small and large lymphocyte percentages between sub-regions C and D. The majority of regions (A and B) were constituted by neutrophils (56% and 66%, respectively), and monocytes accounted for 9% and 7% of the cells, respectively. Large and small lymphocytes were also present in these regions, accounting for 26% and 6% of the cells in sub-region A and 14% and 7% in sub-region B, respectively. In sub-regions C and D, cells were mainly constituted by large and small lymphocytes (33% and 49% in C, and 7% and 70% in D, respectively) and thrombocytes (14% and 23%).
