Abstract: A cell culture unit is disclosed herewith comprising a shell having two ends with an elongated chamber there between. A liquid and a gas perfusion port are located on each end. Liquid perfusion fibers are connected to the liquid perfusion ports and gas perfusion fibers are connected to the gas perfusion ports. These fibers thereby define an extracapillary and intracapillary space. The cell culture unit further comprises means for communicating with the intracapillary space of the gas perfusion fibers means for communicating with the intracapillary space of the liquid perfusion fibers, and means for communicating with the extracapillary space.