Development of a gill perfusion apparatus for studying the interaction of fish pathogens with gill tissue

An isolated perfused gill preparation was developed for the study of the association of gill pathogens with the branchial tissue. The preparation consisted of an excised branchial arch from common carp (Cyprinus carpio L., minimum weight 300g), perfused via the afferent branchial artery. Filtered and heparinised Cortland solution was used as the perfusion fluid and infused by means of a drip (3-litre bag). The average perfusion rate was 1.5ml/minute/arch/kg body weight. The outflowing perfusate was collected from a cannula in the efferent branchial artery. The individual gill arch was suspended in a circular organ chamber filled with Ringer solution, which was aerated and kept at a constant temperature of 20°C. Unperfused gill arches maintained in Ringer solution at the same temperature served as controls. Cortland solution proved to be a satisfactory perfusion fluid, maintaining the perfused gills in a healthy condition for at least 4 hours with no, or only slight, oedema after 90 minutes, and slight or moderate oedema after 4 hours. The unperfused gill displayed excessive necrosis and loss of architecture after 4 hours. The Cortland perfused gill apparatus could thus prove to be an alternative ex vivo model of particular use in the study of the early interaction of gill associated pathogens with the branchial tissue.