Reproduction Abstracts

Introduction: In preparation for blastocyst implantation, the microvilli of uterine epithelial cells (UECs) are lost and the apical plasma membrane flattens. Prominin-1 is a membrane glycoprotein restricted to the apical domain of epithelial cells, while the structurally related prominin-2 is distributed throughout the plasma membrane of epithelial cells in a non-polarised way. This study aimed to examine the expression of prominin-1 and -2 in UECs to examine their potential role in blastocyst attachment and implantation.

Materials and methods: Female virgin wistar rats were mated and tissue was collected at the time of fertilisation and the time of receptivity. Western blotting was performed on isolated UECs and immunofluorescence was performed on cryosectioned tissue. Ishikawa cells, a human uterine epithelial cell line, were also examined by confocal microscopy and western blotting. Deglycosylation analysis was also performed in vitro and in vivo.

Results and discussion: Prominin-1 and -2 are glycosylated in UECs and Ishikawa cells. At both the time of implantation and the time of receptivity, prominin-1 was found to be concentrated in the apical portion of UECs, while prominin-2 was restricted to the basolateral plasma membrane. Prominin-1 expression increased at the time of implantation, whereas prominin-2 expression decreased. These results suggest that prominin-1 may be actively involved in uterine receptivity for blastocyst attachment, while prominin-2 may be lost to allow disassociation of the UECs and blastocyst penetration.