Scientists recognise the advantages animal models can provide to research into human development and disease. There are greater similarities between species, compared to the biochemical and physical differences between them. The differences are taken into account and animal models are selected on how advantageous they will be to the research being carried out. Before animals are used, they will also have been subjected to a variety of other screening processes including the use of computer models, cell cultures and other non-animal tests. Clinical trials in humans also play an important part. Often animal models are used to determine if a full scale clinical trial would be of use, and thus potential saving millions of pounds. Until other suitable alternatives are developed, animal tests will continue to play an important part in minimising the adverse effects to humans caused by unexpected reactions during clinical trials and use.

 This is an organism that carries exogenous genetic material, that has been transferred to it by genetic engineering. Genetic material is transferred to organisms by the use of viruses and bacteria. These are called vectors and integrate into the host's genome.

 These investigate how the organisation of the body plan is achieved during development. They identify the genes involved in the processes of development and how they function. Development includes the creation of pattern, morphogenesis, differentiation and growth. Various experimental techniques and model organisms are used to investigate these.