title: Demonstration of uterine receptivity in vitro by co-culture of rat epithelial cells and blastocyst.
abstract: Uterine receptivity is prerequisite for the attachment of the embryo to the uterine epithelium and involves a specialized polarity-dependent property of uterine epithelial (UE) cells. These UE cells, when polarized in culture, behave like cells in utero by exhibiting apico-basal polarity. In order to develop an implantation model in vitro, UE cells were polarized on extracellular matrix (ECM), and polarity was validated by response to estradiol-17beta administered exogenously. UE cells of pregnant rats at day-3 and day-4 post-coitum (p.c.) and of non-pregnant rats were cultured on bare and extracellular-matrix-coated petri dishes until confluency. Hatched blastocysts were transferred to the cultures, and adhesion was monitored every 24 h. Although blastocysts attached to UE cells that were taken from non-pregnant rats and from rats of day-3 p.c. and cultured on bare plastic, they failed to attach to these cells polarized on ECM. However, blastocysts attached firmly to UE cells that had been taken from rats of day-4 p.c. and polarized on ECM. Receptivity of UE cells taken from non-pregnant and pregnant (day-4 p.c.) rats was quantitated by flow cytometric estimation of cellular levels of beta3 integrin. The expression of beta3 integrin in UE cells from rats of day-4 p.c. was highly significant (P<0.01) when compared with its expression in UE cells from non-pregnant rats. The expression of beta3 integrin in UE cells of day-4 p.c. confirmed the receptivity of these cells to blastocyst implantation. Uterine receptivity was also validated in vivo by inducing the decidual cell reaction in rats ovariectomized on day-3 and day-4 p.c. Whereas remarkable deciduoma was noticed in the animals of day-4 p.c., it was absent in the animals of day-3 p.c., thereby indicating that the uterus was receptive on day-4 p.c. only. Thus, blastocysts do not attach to polarized UE cells that have been obtained from a non-receptive uterus. Attachment will occur only if the cells are obtained from a receptive uterus. UE cell receptivity is therefore essential for mimicking the process of implantation in vitro.
authors.affiliation: Division of Endocrinology, Central Drug Research Institute, P.O. Box-173, 226 001 Lucknow, India.
authors.forename: K R
authors.initials: KR
authors.lastname: Srinivasan
authors.forename: A
authors.initials: A
authors.lastname: Dwivedi
authors.forename: S K
authors.initials: SK
authors.lastname: Jain
authors.forename: P K
authors.initials: PK
authors.lastname: Mehrotra
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology* / Q000502:physiology; D002448:Cell Adhesion; D016764:Cell Polarity; D018920:Coculture Techniques; D004847:Epithelial Cells / Q000166:cytology* / Q000502:physiology; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D039661:Integrin beta3 / Q000032:analysis / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D013997:Time Factors; D014599:Uterus / Q000166:cytology / Q000502:physiology*
chemical_list: D039661:Integrin beta3