Study of gene expression in multiple cell embryo is the most important step in developmental genetic. A large number of regulatory genes and transcription factors have been identified that are involved in early stages ofembryo development. Experience has shown that impaired function and expression of these genes causes major abnormalities in embryos obtained from IVF. Because of importance IGF1 and OCT4 genes in early stage of embryo development of preimplantation . We tried to study possible differences in expression of two these genes during early embryonic stages in bovine. The study of gene expression in the preimplantationembryoof mammals is difficult because the standard proceduresused to quantify mRNA generally require large amountsof starting material. Improvement of of protocols using differentquantitative strategies generally involving the polymerasechain reaction (PCR) has provided new tools for exploration ofgene expression in preimplantation embryos. Thus, in the first step, conditions for gene expression studywasoptimized. RNA was extracted from bovine embryo samples that were produced by IVF, synthesis of cDNA by utilizing of reverse primers OCT4 and Actin was done and multiplex RT-PCR was carried out. Finally, we tried for a comparative analyses of expression of OCT4 , IGF1 genes, in steps 8, 16 and 32 cells. In this study,RT-PCR on the bovine embryo was done for the first time in Iran. Results showed a distinct difference in expressionof OCT4 genein 8 cell stage compared with 32 cell stage.The expression of OCT4 gene was significantly low at the 16 cell stage. Also, our results suggest that IGF1 gene expression in 32 cell stage little more than this for 8 cell stage. It is noteworthy that in the 16 cell stage, there is no detectableexpression for IGF1 and OCT4. Also media conditions in IVF embryo productioncan affect in gene expression.
