Results of the first phase of the ECVAM project "Prevalidation and validation of three in vitro embryotoxicity tests"

The results of the experimental prevalidation of three in vitro embryotoxic ity tests in art ECVAM study are reported. the rat whole embryo culture ass ay (WEC), the micromass assay (MM) and the embryonic stent cell test(EST). Three test chemicals assigned to the three classes of embryotoxicity, non-, moderate- and strong embryotoxic, and also a positive and a negative contr ol chemical were repeatedly tested in each test in two laboratories. The da ta obtained were evaluated independently by a biostatistician. It could be shown that the standard protocols (SOPs) for the three in vitro embryotoxic ity feats could be transferred to a second laboratory and that reproducible results were obtained. The three methods were able to discriminate the tes t chemicals according to their embryotoxic potential. in addition, within t he scope of this study, a test chemical database for in vitro embryotoxicit y testing was established that will be used in the following formal validat ion of the three in vitro tests.