A vessel for housing an organ such as lungs from a mammal ex-vivo, for evaluation or preservation. A liquid solution suitable for evaluation or preservation of the lungs surrounds the organ, at least partly. The solution is circulated via an outlet and an inlet. Two pressure chambers are arranged between the walls of the vessel and the organ. A gas is introducible to the pressure chamber in order to expand the pressure chamber for occupying the spaces surrounding the organ. Then, the pressure inside the pressure chambers is increased in order to push the solution to a higher level so that the organ is immersed in the solution without necessitating addition of further solution. Alternatively, the vessel is exposed to an under pressure and the pressure chambers are open to the atmosphere. In a further alternative embodiment, a solution collection space has variable volume.
