Laboratory models and their role in assessing teratogenesis.

Laboratory models have an important role in identifying exposures with teratogenic potential, determining mechanisms of abnormal development, and supporting or refuting the biological plausibility of associations identified in human studies. Laboratory animals are the most widely used models, but are rapidly being supplemented by in vitro tools. Testing paradigms that have been in place since the mid-1960s for pharmaceuticals, and soon thereafter for industrial chemicals and pesticides, have been used to evaluate the potential developmental toxicity of thousands of agents. These models have served as the principal basis for regulatory decisions about acceptable exposure levels and restrictions on use of certain drugs during pregnancy.