Electron Microscopy of Human Endometrium during Window of Implantation

Abstract

Background: The implantation rate in assisted reproductive technology (ART) remains 25 to 35 percent inspite of marked improvement in the technology. Endometrium is receptive for the process of implantation of the blastocyst only for a span of 3 to 4 days of window of implantation (WOI). During this WOI, certain morphological changes take place in the luminal endometrium. Present study is an attempt to study these ultra-structural changes using scanning electron microscopy (SEM) during hormone replacement cycles (HRT) as the implantation rates are higher in such cycles than in stimulated cycles. Material and Methods: Forty female infertile patients were given the hormone replacement regimen. 6 mg Estradiol valerate was given per day from day 2 of menstrual cycle for 8days. Daily progesterone was supplemented from day 9 by intra muscular route in a dose of 100 mg for 7 days. Sequential endometrial biopsies were performed on 2nd, 5th and 7th day of progesterone. The endometrial (SEM) tissues were subjected for scanning electron microscopy for studying the ultrastructural changes in the luminal endometrium. Results: SEM showed the changes in all the three components of the surface endometrium. The surface epithetlium showed appearance pinopodes all along the surface on 2nd day of progesterone. The pinopodes were found to be fully developed on 5th day and found to be regressed on 7th day of progesterone. The endometrial glands were observed to be maximally developed in number and diameter on 5th day of progesterone. The phenomenon of angiogenesis was also maximally expressed on 5th day of progesterone. Conclusion: Endometrial receptivity is maximally expressed on 5th day of progesterone administration in estrogenic primed patients. Documentation of these changes in one cycle prior to the treatment cycle will help for personalized embryo transfer in oocyte/embryo donation and frozen embryo transfer cycle, to get higher pregnancy rates.