Endometrial markers of uterine receptivity utilizing the donor oocyte model

Background: Ethical constraints limit the ability to study peri-implantation phase human endometrium. In this study, the donor oocyte model was used to study candidate endometrial markers of uterine receptivity. Methods: Archived, paraffin-embedded tissue obtained by endometrial biopsy during cycle days 21-23 of patients undergoing 'mock' hormonal treatment cycles were evaluated by standard histological criteria and immunohistochemical staining for αvβ3 integrin and glycodelin. All of these patients (n = 101) had undergone a donor oocyte embryo transfer cycle utilizing the exact same hormonal protocol. Results: Histological evaluation revealed 62 (61.3%) in-phase, 34 (33.7%) dyssynchronous, 2 (2.0%) immature and 3 (3.0%) advanced endometria. The clinical outcomes of patients with either in-phase or dyssynchronous endometria were similar. Very strong correlations were noted between endometrial glandular dating and either αvβ3 integrin or glycodelin immunostaining intensity (P < 0.001 for both). Glycodelin and αvβ3 integrin immunostaining intensities were also highly correlated with each other (P < 0.001). Conclusions: Throughout the time period corresponding to the putative window of maximal endometrial receptivity (cycle days 21-23) a dynamic process was observed in exogenous hormonal replacement cycles characterized by a rapid histological advancement of endometrial glandular elements as well as progressive αvβ3 integrin and glycodelin expression.