The role of rainbow trout ( Oncorhynchus mykiss , Walbaum) gill cells in uptake of the salmonid pathogen Renibacterium salmoninarum was examined using in vitro , whole animal and isolated perfused head models. Uptake of the pathogen was observed only when dissected gill tissue was exposed to the live pathogen. In contrast, live cells of Yersinia ruckeri interacted with the gill epithelia in the isolated perfused head model, co...