The impact of ovarian stimulation on endometrial histology and the endometrial immunovascular compartment

Ovarian stimulation (OS) exposes the endometrium to supraphysiologic levels of estradiol (E2) and an early rise in progesterone (P4). We examined the glandular, stromal, vascular and immune compartments of the endometrium in order to better understand the mechanisms underlying OS-mediated changes. We hypothesized that OS-mediated changes would be apparent as early as the periovulatory (PO) endometrium and that these changes would persist into the mid-secretory (MSE) phase leading to endometrial aberrations during the window of receptivity.