Association between the extent of DNA damage in the spermatozoa, fertilization and developmental competence in preimplantation stage embryos.

ABSTRACT

OBJECTIVE: To examine the fertilizing ability and DNA damage response of preimplantation stage embryos derived from the γ-irradiated mouse sperm carrying varying amounts of DNA strand-breaks. MATERIAL AND METHODS: The DNA damage in the sperm was induced by exposing the testicular area to different doses of γ-radiation. After mating with healthy female mice, sperm zona binding, fertilizing ability of DNA damaged sperm and developmental competence of embryos derived from the DNA damaged sperm were assessed. RESULTS: The in vivo zona binding ability and fertilizing ability of DNA damaged sperm was significantly affected in the 5.0 and 10.0 Gy sperm irradiation groups. Although the development of the embryos derived from the DNA damaged sperm was not significantly affected until day 2.5 post-coitus, further development was significantly altered, as evidenced by the total cell number in the embryos. CONCLUSION: The sperm carrying DNA strand breaks still has the ability to fertilize the oocyte normally. However, the events like zona-binding and successful fertilization depend on the extent of sperm DNA fragmentation. The study has also showed a great heterogeneity in embryonic development at peri-implantation period with respect to the degree of sperm DNA damage.