Detection of endometrial pinopodes by scanning electron microscopy in hormone-controlled and stimulated cycles

Objective: To assess the effects of clomiphene citrate (CC) and combined oral contraceptive pills (COP) on endometrial pinopode expression.
Design: Prospective study.
Setting: Department of Obstetrics and Gynecology and Department of Histology, Faculty of Medicine, Alexandria university.
Patients: Thirty volunteers with regular menstrual cycles were divided randomly into: group I (n=10) received COP, group II (n=10) received CC and group III (n=10) served as controls.
Interventions: Sequential endometrial biopsies obtained by a pipelle during the luteal phase.
Main outcome measures: Assessment of endometrial pinopodes by scanning electron microscopy (SEM).
Results: Ninety endometrial samples were evaluated under SEM. Fully developed pinopodes appeared in only one sample per cycle indicating their short life span and there were individual variations in the timing of pinopode expression in the same group. COP retarded the appearance of fully developed pinopodes (mean day = 22.4±0.7) whereas CC accelerated their appearance (mean day = 17.9±0.9) compared to controls (mean day = 20.4±0.5).
Conclusions: Advanced endometrial maturation and early pinopode expression in stimulated cycles may reflect shifts in the window of receptivity, resulting in ovo-endometrial asynchrony and limiting implantation success.

Keywords
Endometrium, pinopodes, clomiphene citrate, combined oral contraceptive pills, scanning electron microscopy