Comparison of cornual transfer via laparotomy with utero-cervical transfer of cultured preimplantation rat embryos

Most work on embryo transfer has used the cornual route via laparotomy for implantation. This method is time-consuming and costly in operating materials. Cervical transfer seems to offer a simpler route and the promise of time and cost saving. Technical difficulties, however, have prevented this method from becoming widely used. It was thought that mastery of this technique is essential to allow large-scale experiments in order to determine the optimal time for reimplantation, the optimal stage whether 8 cells, morulae, or blastocysts, and to compare culture media. All of these will have significant clinical applications. In this work Vickery’s method of cervical transfer in mice was modified to include direct vision of the cervix and dilatation before implantation. With this modification equivalent results were found on cervical or cornual transfer, but a higher failure rate on cervical transfer. The results and implications are discussed.