Effects of nitrous oxide on day 9 rat embryos grown in culture.

A rat whole embryo culture system was used to study the adverse reproductive effects of nitrous oxide. Embryos were removed on day 9 of gestation and exposed in culture to several concentrations of nitrous oxide for 24 h. After an additional 25 h of culture, embryos were examined for morphological abnormalities and were assayed later for protein content. Nitrous oxide resulted in growth retardation and an increased incidence of morphological abnormalities and altered body laterality. The conditions required to produce abnormalities were similar to those required in vivo. We conclude that nitrous oxide has direct toxic effects on the developing embryo and that day 9 embryo culture is a useful technique for studying mechanisms of nitrous oxide-induced teratogenicity.