<![CDATA[ Maternal contribution to and direct action of methoxyacetic acid (MAA) on the embryonic development bad been examined by conducting embryo tTansfer. To reveal the maternal contribut ion, compacted morulae and early blastocysts, which were collected from untreated Swiss Webster donor mice on day 3 of gestation, were transferred to day 2 pseudopregnant recipients, after having been treated with 2 .0 mmollkg body weight (b.w.) MAA by gavage on day 1 of pseudopregnancy. Direct effect of MAA on the embryonic development were observed by transferring compacted morulae and early bla tocysts, simi larly recovered from day 3 pregnant donor mice, after MAA treatment on day 2 of gestation with the same method and dosing, to untreated day 2 pseudopregnant recipients. Control donor mice and recipient were given distilled water only as the MAA olvent. Observations on fetuses resulting fTom embryo transfer wert: carried out on day 16 of gestatlOn . Administration of MAA to the donors tended to decrease the unplantatlOn rate and the survival rate of the implanted embryos. W11en MAA was given to the recipients the implantation rate and survival rate of embryos transferred decreased significantly (p<0 .05) but the survival rate of implanted embryos were significantly higher (p<0.05) Lf compared to those of MAA treated donors. The intrauterine death tended to inc rease either in the treated donors or recipients. Th re was no et1ect of MAA on the fetal body weight and in producing fetal malformations . It is concluded that at the beginning of implantation, maternal contribution in revealing the effects of MAA on the embryonic development of Swiss Webster mice is predominant, whereas after Implantation took place, the quality of the embryos become ;lore important for their survival. ]]>
