Spatial and Temporal Analyses of FGF9 Expression During Early Pregnancy

Fibroblast growth factors (FGFs), in complex with their receptors (FGFRs), regulate a broad spectrum of biological functions including cellular proliferation, survival, migration, and differentiation. In human endometrial stromal cells, FGF9 is regulated with estrogen (E).

Our data suggest that FGF9 is a crucial factor required to establish the appropriate microenvironment for successful implantation and the maintenance of pregnancy.

First, we report that in uterus tissue of ovariectomized wild type mice, FGF9 is present in three isoforms and is regulated with E. Second, we found that during peri-implantation, Fgf9 expression reached its peak at day 4.5 of pregnancy. Immunofluorescence analyses demonstrated overlapping FGF9 and COX2 expression surrounding the blastocyst attachment site. Next, we identified FGF9- and CD31-positive cells as a part of the microvessels; however, expression was localized to a distinct population of cells. Finally, our data showed synchronized, spatial expression of FGF9 on the luminal epithelium with FGFR2 present on the trophectoderm.