Abstract
To explain the involvement of leukocytes in defense system of the red sea bream Pagrus major, the kinetics of leukocytes in the peripheral blood and the sequential histopathological changes in the inflammatory foci during artificial infection of Edwardsiella tarda were investigated. In peripheral blood, the lymphocyte count declined and the granulocyte count increased at 1 day post-inoculation (dpi). The monocyte count started to increase from 5 dpi to go to a peak at 15 dpi. In inflammatory foci, the formation of granulomas was characteristic. In the foci, prior to the formation of granulomas, lymphocytes and granulocytes infiltrated, followed by monocytes infiltration. There was strong correlation between the progression of granulomas and the kinetics of leukocytes in the peripheral blood.
