Collection and transfer of preimplantation mouse embryos.

Abstract

An improved method of collection and transfer of preimplantation mouse embryos focusing on increasing the predictability of the mating process and utilizing artificial insemination and artifical induction of pseudopregnancy is presented. Donor females were superovulated by the injection of 10 IU pregnant mare's serum followed 60 hours later by 10 IU human chorionic gonadotropin. Immature C3HeB/J females were treated with 6 IU of the 2 hormones on exactly the same schedule. In some foster mothers the estrous cycle was phased with the administration of 1.5 or 3.0 IU of the gonadotropins. Artificial insemination and artificial inductions of pseudopregnancy were performed 12 hours after the 2nd injection. The appropriate time of artificial insemination or induction was predicted in animals untreated with hormones, on the basis of estrous smears. A modification of artificial insemination techniques, refraining from use of the artificial penis and vaginal tampon, was used. Embroys were flushed from the oviducts of females 36 hours after insemination. Attainment of the 2-celled stage was evidence of fertilization. Embroys were maintained in vitro and then transferred to foster mothers at the early blastula stage. 5 embroys were transferred to each uterine horn. Implantation was evaluated. The yield of embroys was doubled through the use of artificial insemination. 1 male was used to inseminate up to 20 females. It was found that selection of recipients from normally cycling females was preferable to hormone priming.