Fig. 1: Diagram of a hollow-fibre cartridge. Access to the intracapillary space is via the end ports and to the extracapillary space is via the side ports. The close-up view (bottom) shows cells attached to the external surface of the fibres. Alternative arrangements include the use of cells grown on microcarrier beads that float in the extracapillary space or cells grown in the intracapillary spaces. Modified from Sussman and associates.[20]