Repeated Use of Surrogate Mothers for Embryo Transfer in the Mouse

Abstract

Embryo transfer in mice is a crucial technique for generation of transgenic animals, rederivation of contaminated lines, and revitalization of cryopreserved strains, and it is a key component of assisted reproduction techniques. It is common practice to use females only once as surrogate mothers. However, their reuse for a second embryo transfer could provide hygienic and economic advantages and conform to the concept of the 3Rs (replace, reduce, refine). This investigation evaluated the potential for a second embryo transfer in terms of feasibility, reproductive results, and experimental burden for the animal. Virgin female ICR mice (age 8-16 wk) were used as recipients for the first embryo transfer. Immediately after weaning of the first litter, a second surgical embryo transfer was performed into the same oviduct. Virgin females of comparable age to the reused mothers served as controls and underwent the same procedure. The first surgery did not affect the success of the second embryo transfer. Histological sections showed excellent wound healing without relevant impairment of involved tissues. We observed no differences in pregnancy rates or litter sizes between the transfer groups. Most importantly, we found no change in behavior indicating reduced well-being and no increase of corticosterone metabolites in the feces of surrogate mothers reused for a second embryo transfer. We conclude that a second embryo transfer in mice is feasible with regard to reproductive and animal welfare aspects.

Success of embryo transfer in mice with freshly collected and cryopreserved two-cell embryos with different genetic backgrounds correlated with the number of transferred embryos: A 5-year retrospective analysis

“…Therefore, the results presented here for the outcome after embryo transfer of freshly collected or cryothawed embryos might be inferior to results published earlier. 10,11 Nevertheless, we thought that retrospective analyses of more than 1300 embryo transfers could give an overall estimation for better planning and performance of embryo transfers, because heterogeneity of the background strains was equal for all groups and could therefore be disregarded here. The number of transferred freshly collected embryos influenced the pregnancy rate.…”

Embryo transfer manipulation cause gene expression variation in blastocysts that disrupt implantation and offspring rates at birth in rabbit

“…It has been demonstrated that suboptimal conditions during the periconception period induce gene expression and epigenetic changes in gametes and embryos that can be maintained during post-implantation development [2]. In particular, alterations have been described at genetic and epigenetic level in placentas derived from in vitro fertilization, intracytoplasmic sperm injection or in vitro culture of embryos [22,23,24].…”

Assessment and refinement of intra-bone marrow transplantation in mice

“…27 As we can exclude external stressors, we assume that this is a residual impact from the prior five-day training period.…”