The expression of apoptosis-related proteins Bcl-2 and Ki67 in endometrium of ovulatory menstrual cycles

Background. During the menstrual cycle, a rapid sequence of proliferation, differentiation and cell death occurs in the human endometrium. Mechanisms involved in cell proliferation have been studied extensively. Apoptosis has recently been recognized to be a physiologic phenomenon. The aim of this study was to investigate the mechanisms involved in hormone-dependent tissue remodeling by measuring Bcl-2, an apoptosis inhibitor, and Ki67, a proliferation marker, as expressed in normal human endometrium. Methods: Paraffin-embedded endometrial sections of 30 uteri were immunostained for Bcl-2 and Ki67; expression was scored in cavitary epithelium, functional and basal glandular epithelial and stromal cells of the endometrium. Results: Bcl-2 expression increased in the proliferative phases and decreased significantly in the secretory phases, especially in glandular epithelial cells (131 +/- 45 for functional laminal cells and 227 +/- 68 for basal laminal cells to 0). Ki67 expression showed the same cyclic pattern with a later onset (145 +/- 63 for functional laminal cells and 13 +/- 8 for basal laminal cells to 0). Conclusion: Bcl-2 promotes cell survival by preventing apoptosis. Proliferation is the result of increasing estradiol concentration, high estrogen receptor expression and growth hormones and high Bcl-2 and Ki67 expression. After the onset of progesterone production, Bcl-2 levels decrease and Ki67 levels and androgen receptor expression in stromal cells disappear resulting in cell disintegration and menstruation. Persistent Bcl-2 expression, like we saw in basal laminal stromal and epithelial cells, accounts for the privilege of escaping from apoptosis-inducing signals. This allows reconstruction of the functional endometrium from its preserved basal layer after menstruation. Copyright (C) 2002 S. Karger AG, Basel

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 5 alpha -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. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved

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 5 alpha -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. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved