Pilot Test of Embryo Transfer in Murine at the National University of La Plata, Argentina

Abstract

Introduction: Embryo transfer in murine models is a fundamental technique in biomedical studies, particularly in reproductive biology, genetic modification, and transgenic animal production. Successful implementation of this method requires appropriate laboratory infrastructure, technical expertise, and careful standardization of procedures. The present study aimed to report the first pilot embryo transfer in mice at the National University of La Plata, Argentina, and to evaluate the technique's initial feasibility and efficiency.
Materials and methods: Embryos were generated by ovarian superovulation in an 8-week-old female C57BL/6J donor mouse using a single intraperitoneal injection of 10 IU of equine chorionic gonadotropin (eCG), followed 48 hours later by 10 IU of human chorionic gonadotropin (hCG). The donor female mouse was subsequently mated with a fertile C57BL/6J male mouse. The following day, the mucus plug in the donor female was examined and then euthanized by cervical dislocation. Single-cell embryos (zygotes) were obtained. Thirteen fresh embryos were surgically transferred into a 12-week-old pseudopregnant Swiss recipient female mouse using the conventional oviductal transfer technique.
Results: A pregnancy rate of 61.5% was achieved following embryo transfer. The transferred embryos were one-cell zygotes collected at 0.5 days post-coitum. Eight live pups were delivered at 19.5 days post-coitum and exhibited normal postnatal development. The pups were weaned at 21 days of age. The litter consisted of five males and three females. The administration of preoperative analgesia and the use of a standardized anesthesia protocol contributed to a favorable postoperative recovery in the recipient female mouse.
Conclusion: This successful pilot study can help establish local murine strain banks in Argentina, where such infrastructure is currently lacking, and highlights the potential to fully implement and benefit from cryopreservation technologies.