Abstract:

Successful embryo implantation is a complex process, which is well regulated by both embryo and endometrium. The precise synchronization between the blastocyst and maternal endometrium is very important. Pinopode, a special cellular process expressed in the endometrium, shows different morphologies with the menstrual cycle, which can be divided into the developing pinopode, the maturated pinopode and the degeneration pinopode. A series of clinical studies have proved that the number, the size of coverage area and the development stage of pinopodes have clinical value in predicting the implantation window and assessing the endometrial receptivity in infertile women. Women with higher pinopode score and wider coverage size of pinopodes, and higher proportion of well developed pinopodes, will have better pregnancy outcomes. The mechanism may include that pinopodes affect the endometrial receptivity by regulating uterine contents, and that pinopodes participate in the blastocyst-endometrial interaction by expressing implant-related proteins. However, the accurate and objective assessment method of pinopode still needs to be explored, while the accuracy of its assessment of endometrial receptivity also needs to be further evaluated.

Key words: Endometrium, Menstrual cycle, Embryo implantation, Pregnancy outcome, Pinopode