3.3.2. NOTCH Signaling in Blastocyst Adhesion to the Endometrium

The expression of NOTCH receptors and ligands in the trophectoderm of the blastocyst and that of NOTCH1, DLL4, and JAG1 in the apical surface of the endometrial epithelium during the mid-secretory phase [170,256] would suggest a role for NOTCH signaling in the adhesion of the blastocyst to the epithelium. Indeed, it has been demonstrated that blastocyst-conditioned medium regulates NOTCH1 and JAG1 expression in the endometrial epithelium [256], suggesting that the blastocyst is able to activate NOTCH signaling in the endometrium, thus possibly regulating its receptivity. This is reinforced by the fact that women with primary infertility show a reduced or absent immunostaining for JAG1 in the luminal epithelium during the mid-secretory phase [256].
