Whole embryo culture: a screening technique for teratogens?

Head-fold and early somite stages of mouse and rat embryos maintained in whole-embryo culture throughout much of the period of organogenesis demonstrate normal growth and morphogenesis. Embryos directly exposed to teratogens in the culture system and embryos cultured in serum from adult animals treated with toxic compounds develop congenital abnormalities that resemble malformations induced in vivo by these same agents. Furthermore, the defects are dose- and stage-dependent, such that higher doses produce a greater percentage of malformed embryos, and younger embryos are more susceptible than older ones. These results--together with the observations that 1) data are rapidly produced, 2) quantifiable endpoints can be measured in mammalian systems at costs considerably below those inherent in in vivo analyses, and 3) the potential exists for monitoring serum toxicity in humans and primates--suggest that the whole-embryo culture system may be useful as a screening technique for potentially teratogenic substances.