Steroid-regulated molecular markers of implantation

The endometrium acquires the ability to implant the developing embryo withi n a specific time window, termed the "receptive phase." During this period the endometrium undergoes pronounced structural and functional changes indu ced by the ovarian steroids estrogen and progesterone, which prepare it to be receptive to invasion by the embryo. These steroid-induced molecules, wh en identified, may serve as useful markers of uterine receptivity. In the p resent article, we provide a brief description of the molecules that have e merged as candidate markers of steroid hormone action in rodents and humans during implantation.