Application of the post-implantation rat embryo culture system to in vitro teratogenicity testing.

Originally developed for studying basic mechanisms in developmental biology, the post-implantation embryo culture system has been extended and applied to the testing of chemicals in the field of prenatal toxicology. The endpoints used in a procedure that has been developed for the routine short-term assessment of teratogenicity in vitro are growth (crown-rump length), differentiation (somite number) and morphology (together with measurement of yolk-sac growth and vascularization) in rat embryos explanted on day 9.5 of gestation and cultured for 48 hr in 100% homologous rat serum containing the test compound. Studies involving exposure to trichlorophenoxyacetic acid and to acetylsalicylic acid demonstrate the ability of this system to distinguish between non-specific toxicity and specific effects on development.