Effect of RU486 on development and implantation of rat embryos

Luis S. Roblero, Horacio B. Croxatto

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34 Citations (Scopus)


This study evaluated the effects of postcoital treatment with the antiprogestin RU486 on transport, development and implantation of rat embryos. Doses of 0.1, 0.5, 1.0, 2.0, or 3.0 mg/rat of RU486 were injected subcutaneously on days 1, 1+2, or 4 of pregnancy. Autopsies were carried out on days 5 or 12 of pregnancy. RU486 provoked a significant dose‐related reduction in the number of recovered embryos and inhibited their development (day 5) and decreased the number and size of implanted embryos (day 12). Treatment on day 4 was the least effective. Blastocysts recovered from RU486‐treated rats exhibited comparable rate of trophoblastic outgrowth in vitro as the controls. Blastocysts transferred from RU486‐treated rats to synchronous untreated pseudopregnant recipients yielded implanted embryos 12 days later in all recipients, although at a significantly lower rate than the controls. Blastocysts transferred from control pregnant rats to RU486‐treated pseudopregnant recipients failed to implant completely when the dose was ≥ 1.0 mg. The interceptive mechanism of postcoital treatment with RU486 in the rat involves loss of embryos from the reproductive tract and altered development prior to implantation. Endometrial receptivity or the ability of the uterus to retain the embryos until the time of implantation are also impaired by RU486. The embryos that survive these effects may experience delayed implantation in their mothers.

Original languageEnglish
Pages (from-to)342-346
Number of pages5
JournalMolecular Reproduction and Development
Issue number4
Publication statusPublished - 1991


  • Embryo development
  • Oviductal transport
  • Rat embryo transfer
  • RU486

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Cell Biology


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