Steroid-regulated molecular markers of implantation.

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