0000000000776784
AUTHOR
John D. Aplin
Human Endometrial Mucin MUC1 Is Up-Regulated by Progesterone and Down-Regulated In Vitro by the Human Blastocyst1
Expression of MUC1 in endometrial epithelium has been suggested to create a barrier to embryo attachment that must be lifted at the time of implantation. In this study, we investigated the hormonal regulation of human endometrial MUC1 in hormone replacement therapy cycles and in the human blastocyst. We also analyzed the embryonic regulation of MUC1 in human endometrial epithelial cells (EECs) during the apposition and adhesion phases of human implantation using two different in vitro models. Our results indicate that endometrial MUC1 mRNA and immunoreactive protein increase in receptive endometrium compared to nonreceptive endometrium. Human blastocysts express MUC1, as demonstrated by rev…
MUCI, glycans and the cell-surface barrier to embryo implantation
As it approaches the maternal surface, the attaching embryo encounters the epithelial glycocalyx, which contains the mucin, MUC1. A high density of MUC1 at the cell surface can inhibit cell adhesion. This raises the possibility of the existence of a uterine barrier to implantation that might allow maternal rejection of poorer quality embryos. To investigate the mechanism of implantation, human embryos were incubated with endometrial epithelial monolayers. Hatched blastocysts were found to attach readily to the epithelial surface. MUC1 was lost from epithelial cells beneath and near to the attached embryo, while normal expression persisted in neighbouring cells.