Scanning electron microscopy of postovulatory human endometrium in spontaneous cycles and cycles stimulated by hormone treatment

Abstract

The ultrastructure of the luminal surface epithelium was compared in endometrial samples taken from 23 normally cycling women and from 22 patients submitted to ovarian stimulation with clomiphene citrate (100 mg/day for 5 days), human menopausal gonadotrophin (hMG) and human chorionic gonadotrophin (hCG). On day 2 after ovulation, only four out of nine specimens taken from the women in the hormone-treated group were identical to those of normally cycling women. On day 6 after ovulation, only two out of the 13 biopsy specimens from the treated group were the same as those from normally cycling women at that stage. Apical protrusions (pinopodes), typical for this period of the cycle, were missing in 11 of the 13 endometrial samples from the treated group. These observations suggest that the hormonal treatment applied to induce ovulation (clomiphene citrate, hMG and hCG) can modify the normal development of the prenidatory endometrium, and may thus have a negative effect on the rate of egg implantation.

Endometriosis and Inflammation in Infertility

“…99 Scanning electron microscopy demonstrates that 78% of endometrial biopsies obtained from normal cycling women on postovulatory day 6 have pinopods compared with rare pinopods on postovulatory days 2 or 9. 100,101 Garcia-Velasco et al 102 in a prospective study evaluated pinopode formation in women with and without endometriosis who underwent oocyte donation, and they could not find a difference between the two groups.…”

Embryonic implantation: cytokines, adhesion molecules, and immune cells in establishing an implantation environment

“…An adhesion-related phenomenon that appears to be relevant in implantation is pinopode formation (sometimes referred to as an uterodome). Pinopodes can be found on the luminal epithelium of the human endometrium during the window of implantation [95]. Pinopodes are progesterone-dependent organelles that appear on the apical surface of the epithelial cells as cellular protrusions.…”

Understanding implantation window, a crucial phenomenon

“…They were first described in mice[5] and later in human endometrium. [67] The term ‘pinopod’, derived from the Greek word ‘drinking foot’. Electron microscopy is the major tool used to observe these structures.…”

“…Electron microscopy is the major tool used to observe these structures. [67] Pinopod expression is limited to a brief period of maximum 2 days in the menstrual cycle corresponding to the putative window of implantation. [89] Others have detected that pinopods are present throughout the mid- to late-secretory phase, however, displaying cycle-dependent morphological changes.…”