For a long development process - such as the tissue engineering of replacement organs - to run to completion, there must be profitable uses for early, intermediate progress. Profit makes the world go round, after all. This EurekAlert! release looks at what can be done with slight advances in building complex tissue from scratch: "biomedical engineers can now grow and assemble living microtissues into complex three-dimensional structures in a way that will advance the field of tissue engineering and may eventually reduce the need for certain kinds of animal research. ... There is a need [for] tissue models that more closely mimic natural tissue already inside the body in terms of function and architecture ... We think this is one step toward using building blocks to build complex-shaped tissues that might one day be transplanted." Research using cultured tissue will in due course be far cheaper than animal studies, which means that it will be widely adopted. This in turn will help to fuel advances towards the ultimate goal of building new tissue to repair age-damaged human organs.