ABSTRACT
Perfusion permits culture homogeneity rather than a feed-and-fast regime, and has permitted the development of bioreactors which have no gas headspace and significant scale-up of cell density. A wide range of culture systems has been reviewed with the emphasis on attached cells. The prime objective of using perfusion techniques is to achieve a controlled and homogeneous environment within the bioreactor. The use of perfusion to keep small fragments of tissue viable in microscope chambers developed in complexity between 1912 and 1970, culminating in Rose's dual-rotary circumfusion system. The cytogenerator also encouraged the development of perfusion systems for substrate or anchorage-dependent cells. The use of perfusion techniques carries this risk because of continuous entry and exit of materials from the reactor, often through vulnerable tubing in pumps, etc. Both the bioreactor and the associated equipment should be critically evaluated with this in mind.
