ULTRASTRUCTURAL CHARACTERISTICS OF THE LUTEAL-PHASE ENDOMETRIUM IN PATIENTS UNDERGOING CONTROLLED OVARIAN HYPERSTIMULATION

Objective: To provide a descriptive analysis of the ultrastructure of the endometrial surface epithelium during the luteal phase from patien ts undergoing controlled ovarian hyperstimulation (COH). Design: Prosp ective, observational study. Setting: Tertiary care academic IVF cente r. Patient(s): Twelve oocyte donors undergoing COH. Intervention(s): A fter oocyte aspiration, patients underwent two endometrial biopsies 2 to 7 days after hCG administration. Main Outcome Measure(s): Appearanc e of the endometrial epithelial surface as evaluated by scanning elect ron microscopy. Result(s): Endometrial maturation proceeded in an orde rly manner. The ciliated cells remained unchanged, both in regards to cell density, cilia density, and ratio of ciliated cells to nonciliate d cells. The microvilli became more uniformly distributed as the lutea l phase progressed. The central aspect of the cells also appeared to p rotrude more into the endometrial lumen as the cycle progressed. Elong ation the glandular orifices also was noted with progression of the lu teal phase. Apical protrusions, pinopods, were noted to develop and re gress during a short period during the midluteal phase spanning days 4 to 7 after hCG administration. Initial pinopod development began in t he region of the glandular orifices, with substantially fewer occurrin g outside this region. Conclusion(s): Although the development of the endometrial ultrastructural characteristics during the luteal phase pr ogresses in an orderly manner that is comparable to that of endometriu m obtained in unstimulated cycles, pinopod expression was noted at an earlier phase of endometrial maturation. This advanced development may result in an alteration the window of implantation and affect pregnan cy rates in women undergoing COH. (C) 1997 by American Society for Rep roductive Medicine.