Fibroblast growth factors (FGF) are a large family of growth factors which are ubiquitous in the body and play varied roles. Hitherto, 23 FGFs has been identified in mammals. FGFs induce cell growth, differentitation, migration and apoptsis. Four types of membranic fibroblast growth factor receptors (FGFR1/2/3/4) transmit the FGFs signals to the cell. Embryonic lineage markers are often synthesized in a specific embryonic lineage and also are engaged in determination of differential status of the lineages. Several studies have described the effects of FGFs on embryo development. However, there are few studies on ovine embryos. Present study concerned the existence of FGFRs in pre-implantation ovine embryos. Moreover, we investigated the effect of FGF2 and PD173074 as a stimulator and inhibitor of FGF signaling, respectively, on ovine embryo development from day 1 to day 8 post-IVF. The parameters followed in the present study were: 1) blastocyst formation rate, 2) blastocyst quality (cell numbers) and 3) expression level of embryonic lineage markers. Therefore, the effect of FGF2 and PD173074 on these parameters was assayed compared to untreated (control) group. Furthermore, the expression level of seven embryonic (or stem cell) lineage markers, including Sox2, Rex1, Oct4 and Nanog as epiblast markers; Gata4, as primitive endoderm marker and IFNT and Cdx2 as trophoblast markers were assessed via Real-time PCR. The results showed that FGFRs transcripts exist in ovine embryos and their highest expression level appear at the morula stage. Supplementation of FGF2 or PD173074 did not change the blastocyst formation rate or quality. However, FGF2 could alter the expression level of three embryonic lineage markers (Gata4, Nanog and Cdx2). Therefore, the FGF signaling may be a regulator of embryonic lineage segregation. Key Words: Fibroblast growth factor, Ovine embryo, Lineage marker
