Xenobiotic influences on embryonic differentiation, growth and morphology in vitro

Direct in vitro exposure of post-implantation rat embryos to 18 known teratogens induced typical malformations in all cases. Of 21 non-teratogens in vivo, 20 induced, in vitro either no malformations at all, even at high concentrations, or abnormal development could only be observed at concentrations which affected growth and differentiation significantly. Responses of chemically induced exposed embryos in vitro occurred within wide concentration ranges. Actinomycin D, for example, affected embryonic development at a concentration as low as 3 X 10(-4) micrograms/ml, whereas other substances had no effect at concentrations up to 9 X 10(2) micrograms/ml.