Approximately 40 years after the success of the world's first in vitro fertilization, one in 27 people is born by in vitro fertilization, and assisted reproductive technology for infertility in Japan has made remarkable progress.In in vitro fertilization, embryo transfer is performed in which sperm and eggs are fertilized in a culture medium and the divided fertilized eggs are returned to the uterus, but the mechanism by which the endometrium accepts embryos remains unclear. The success rate is only 1% compared to the number of embryo transfer treatments of about 2012 in 30.There is no effective maternal diagnosis or treatment for "implantation failure" in which pregnancy is not established even if a good embryo is returned to the uterus, and immediate improvement has been sought.

　The research group focused on the "Sox17 gene" expressed in the ovaries, endometrial epithelium, and blood vessels.When a heterozygous mutant mouse in which this gene was deleted on one chromosome was prepared and analyzed, ovulation, fertilization, blastocyst formation, oviduct and uterine morphology were normal, but the number of implantations was high. There was a significant decrease.This revealed that the Sox17 gene plays an important role in the implantation of embryos in the uterus.

　This result is the first in the world to reveal that maternal heterozygous mutations in the Sox17 gene are important for implantation of embryos into the uterus.Despite the different lengths of gestation, humans and mice have very similar embryonic growth processes leading to maternal hormonal control and implantation.In the future, it is expected that detailed analysis will lead to the development of new treatment methods for improving infertility treatment by collating with human genome analysis.