INTERLABORATORY EVALUATION OF EMBRYOTOXICITY IN THE POSTIMPLANTATION RAT EMBRYO CULTURE

The embryotoxicity of eight xenobiotic compounds in rat postimplantati on whole embryo culture was blindly tested in four laboratories accord ing to a standard protocol. The results show that the four nonteratoge ns amaranth, penicillin, isoniazid, and saccharin did not affect embry ogenesis apart from general toxicity at very high concentrations in cu lture for amaranth and isoniazid. There was good concordance of result s across the laboratories. The four teratogens (retinoic acid, 6-amino nicotinamide, acetylsalicylic acid, and vincristine) induced a variety of specific embryotoxic effects, which were in most cases similar in all laboratories. These results indicate that the definition for speci fic embryotoxicity used, as well as the culture duration and embryonic age are crucial for concordant scoring. Other methodologic difference s did not significantly influence scoring of embryotoxicity. Therefore , within the limits of the end points and embryonic stage represented in the method, embryo culture appears as a useful method for embryotox icity screening, which can be reproducibly applied in different labora tories.