Apoptosis and expression of the proto-oncogenes bcl-2 and c-myc in normal endometrium through the human menstrual cycle

Apoptosis (AP) in human endometrial cells during the secretory menstrual ph ase (SP) has been suggested to play an important role on the reception of t he embryo. Our purpose was to detect AP by TUNEL, Bcl-2 by immunohistochemi stry, and the bcl-2 and c-myc expression by reverse transcription-PCR. Endo metrium samples were obtained from healthy patients undergoing hysterectomy or mini-laparotomy for tubal sterilization. The results revealed apoptotic cells (93 % of epithelial cells versus 73 % of stromal cells) which were r estricted to the superficial third of mid secretory endometrium, but not in proliferative phase (PP). Phagocytes with apoptotic bodies were observed m ostly during late SP in the lumen of the glands. On the other hand, Bcl-2 w as detected in PP mostly in basal glands and RNA coding for bcl-2 and c-myc was present in both phases. This study suggests an induction of AP in mid SP, which can be hormonally regulated through a decrement of Bcl-2 synthesi s.