Pregnancy and live birth from nonsurgical transfer of in vivo- and in vitro-produced blastocysts in the rhesus monkey

Embryo transfer in the rhesus monkey has been historically limited to trans fer of cleavage stage embryos. In order to allow genetic manipulation of rh esus embryos in vitro, without using invasive surgical techniques, it is im portant to explore the transfer of morula and blastocyst stage embryos. Emb ryos were produced by in vitro fertilization from gonadotropin-stimulated m onkeys, or were obtained by nonsurgical uterine flushing of naturally mated or artificially inseminated females. Nonsurgical transfer was accomplished by inserting a metal guide through the cervix into the uterus, after which a hollow cell sampler was inserted over the guide. The guide was removed a nd a catheter was inserted containing one to five embryos. Several pregnanc ies resulted from in vitro- and in vivo-derived blastocysts, and two pregna ncies were carried to term resulting in one live birth. Blood samples were collected regularly to monitor plasma levels of chorionic gonadotropin, lut einizing hormone, and progesterone. The recipients received progesterone as a subcutaneous implant or daily injections from the day of transfer. The a pproach described in this study provides the opportunity to explore transge nic and chimeric models in the monkey by the development of noninvasive met hods to transfer late-stage embryos that have been manipulated in vitro.