Ovarian markers of implantation potential in assisted reproduction.

In-vitro fertilization provides evidence for the heterogeneity of human embryos; data from the UK indicating that approximately 90% of embryos selected for transfer fail to implant. The need to identify factors that promote implantation or markers of implantation is self-evident. There is an increasing awareness that the heterogeneity of follicles may have a significant impact on oocyte competence and embryo viability and that factors which contribute to the heterogeneity of follicles may provide markers of implantation in assisted conception. The markers of implantation described include the expression of 11 beta-hydroxysteroid dehydrogenase by granulosa cells in vitro; adhesion and proliferation of cumulus cells in vitro; steroidogenic activity of cumulus in vitro and perifollicular vascularity and vascular endothelial growth factors bound to granulosa and cumulus cells. These factors may provide clinically useful markers of implantation potential.