NONSURGICAL METHOD FOR THE INDUCTION OF DELAYED IMPLANTATION AND RECOVERY OF VIABLE BLASTOCYSTS IN RATS AND MICE BY THE USE OF TAMOXIFEN AND DEPO-PROVERA

Implantational delay in rats and mice is experimentally induced by wit hdrawal of oestrogen and maintenance of progesterone, The oestrogen is normally removed by ovariectomy. We report here that the use of the a ntioestrogenic effect of the drug tamoxifen in combination with Depo-P rovera (which counteracts the oestrogenic effects of the tamoxifen) ma y be used to put the embryos both of rats and mice into delay of impla ntation. These delayed embryos retain their developmental potential an d give rise to live born young when transferred to pseudopregnant reci pient females. They are a good source of ES cells. Mol. Reprod. Dev. 5 2.29-32, 1999. (C) 1999 Wiley-Liss, Inc.