[Objective] The research aimed to observe the effects of Escherichia coli infection on the morphology of hemocytes of the 3rd stage larva of Musca domestica in vitro and understand the hemocytes types that take part in the cell immunity of Musca domestica larval.[Method] The hemcytes of the 3rd stage larva of Musca domestica were cultured in vitro and the hemocyte morphology was observed about 2,4,6,8 h after culture in vitro.After Escherichia coli were injected into the hemocytes of the 3rd stage larva of Musca domestica in vitro,the morphology changes of hemocytes were observed at different time after infection.[Result] The hemocytes of of the 3rd stage larva of Musca domestica was divided into five types about 2 h after hemoculture.The hemocytes partly adherence was seen about 6 h after hemoculture.The vacuolation and morpholysis was found in plasmatocytes after being infected by E.coli and a great quantity bacterium were gathered around granulocyte,but the morphology changes of hemocytes were not found in the prohemocyte,shprulocyte and oenocytoid.[Conclusion] The plasmatocyte and granulocyte were primary participants of the cell immunity of Musca domestica larval,but the prohemocyte,sphrulocyte and oenocytoid do not participate in the cell immune reactions.
