Effects of mifepristone on ultrastructure of human endometrium in the early secretory phase

AIM:To investigate the influence of mifepristone on ultrastucture of human endometrium in the early secretory phase. METHODS: Endometrial tissue was obstained from 10 patients of reproductive age, who underwent a hysterectomy within 1 week postovulatory for gynecologic diseases not involving the endometrium. Patients were divided into mifepristone group (n=5) and control group (n=5) randomly. Each patient in the mifepristone group had taken 25 mg mifepristone per os 24 h before the operation was performed, while none of the control group had taken mifepristone. After removal of uterus, endometrial tissue was immediately acquired and prepared for electron microscopic examination. RESULTS:In comparison with the control group, the endometrial tissue in mifepristone group displayed the following distinctly morphological changes: (1) In the endometrial epithelium neither nucleolar channel system nor giant mitochondrium was seen, and subnuclear glycogen accumulation was seldom observed, but giant lysosomes were frequently found. (2) The intercellular spaces of the epithelium were narrow and straight, the indigitations of lateral plasma membranes were rarely visible. (3) Cytolysis and karyopyknosis of stroma cells and extravasal red cells were repeatedly observed.CONCLUSION:The above ment ioned morphological changes in endometrium in the early secretory phase caused by mifepristone are undoubtedly sufficient to prevent implantation.Consequently, mifepristone may have a contraception effect.