Role of Estrogen Recpetor in the Implantation and Post-Implantation Embryo Development

  • Huang, Fu-Jen (PI)
  • Chan, Wen Hsiung (CoPI)
  • Huang, Kuo-En (CoPI)
  • Kang, Hong-Yo (CoPI)
  • Lan, Kuo Chung (CoPI)

Project: National Science and Technology CouncilNational Science and Technology Council Academic Grants

Project Details


Estrogen plays an important role in normal pre-implantation, embryonic development in the reproductive tract, and the changes of uterine endometrium induced by estrogen have been well documented. However, the influence of high levels of E2 during embryonic implantation is still controversial. Elevated ratios of estradiol to progesterone were shown to inhibit blastocyst metabolism and implantation. In the studies of assisted reproductive technology (ART), they has been reported that controlled ovarian hyperstimulation (COH) used for ART inhibits embryo implantation. It has been proposed that high E2 levels after COH impair endometrial receptivity. It appears to be important to maintain the concentrations of estrogen and progesterone at appropriate levels relative to each other. However, it is not clear whether the hormones acted directly on the embryo or indirectly through the mother's reproductive tract. The effects of estrogen depend on the existence of their specific receptors. Estrogen receptor (ER) mRNA was found in oocytes and fertilized eggs. The message level began to decline at the two-cell stage and reached its lowest level at the five- to eight-cell stage. It was not detectable at the morula stage but reappeared at the blastocyst stage. Interestingly, ER mRNA was detected at the blastocyst stage and was likely of embryonic and not maternal origin. The embryonic expression of ER genes in the blastocyst suggests a possible functional requirement for ER at this stage of development. Since estrogen elicits its functions primarily through its receptor protein, a direct estrogen effect on the blastocyst should require the presence of ER protein in the blastocyst. A direct demonstration of ER expression at the protein level was studied in 1996. These findings that ER is present in both the inner cell mass and trophectoderm cells in the blastocyst and that ER expression persists at least until the early egg cylinder stage in all cell types suggests that ER may be important for implantation and/or early embryogenesis. To examine whether estrogen has a direct influence in the implanting blastocyst and early egg cylinder embryo, we employed in vitro culture systems which obtaining an environment without the complication of maternal effects. These systems have been used by our lab and others to mimic certain aspects of post-implantation embryonic development. To date, there is no literature regarding the direct action and the mechanism of estrogen on the implanting and early egg cylinder embryo. In this series of studies, we will use the model to evaluate the physiological and pharmacological role of estrogen in the implanting blastocyst and early egg cylinder embryo.

Project IDs

Project ID:PC10107-0220
External Project ID:NSC101-2314-B182A-110
Effective start/end date01/08/1231/07/13


  • estrogen receptor
  • implantation
  • blastocyst
  • postimplantation embryodevelopment


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