Androgen, estrogen and progesterone receptor expression in the human uterus during the menstrual cycle

Cyclic changes in steroid receptor expression in endometrial cells are considered a reflection of its differential functions. Besides estrogen and progestogens, androgens have also been suggested to affect the biological function of the female reproductive tract. We investigated the distribution and intensity of immuno-cytochemical estrogen receptor (ER), progesterone receptor (PR) and androgen receptor (AR) staining in the various cell types of human endometrium and myometrium during the different menstrual cycle phases in 30 paraffin-embedded sections. AR expression in endometrial stromal cells decreased gradually from early proliferative till mid secretory phase. In the late secretory phase, AR expression in all cell types distinguished. Staining of epithelial cells was moderate. The disappearance of AR expression before cyclic separation of endometrial tissue may be causally related or just an epiphenomenon. Due to local competition for 5α-reduction of testosterone and the excess of progesterone in the secretory phase, the level of dihydrotestosterone (DHT) will be diminished. Hypothetically, if AR synthesis in endometrium would be DHT-dependent, it would explain the lack of AR expression in the late secretory phase.