The In vitro Fertilization of Ovine Oocytes in the Presence of Oviductal Cells and its Effect on the Expression of Zygote Arrest 1 (Zar1) and Subsequent Embryonic Development

Background: The cells of mammalian female reproductive tract have been widely used for in vitro fertilization (IVF). This study was designed to study the effects of oviductal epithelial cells (OECs) and their conditioned medium during IVF on subsequent embryonic development and the relative abundance of zygote arrest 1 (Zar1) transcript in ovine zygotes. Methods: The in vitro matured ovine oocytes were randomly fertilized in the following culture conditions: I) SOFaaBSA+20% sheep serum (control), II) SOFaa BSA+20% sheep serum (50 μl) in the presence of OECs, III) SOFaaBSA+20% sheep serum (100 μl) in the presence of OECs, and IV) OECs conditioned medium (CM). Sigma Stat (Version 2.0) software and one-way ANOVA were considered for statistical analysis. A p<0.05 was considered statistically significant. Results: The cleavage, blastocyst, and hatched blastocyst rates in OECs and CM groups were significantly lower than the control group (p<0.01). In co-cultured groups, the application of two different volumes of IVF medium showed no difference in embryonic developmental indices. The Zar1 gene expression in zygotes produced in the presence of OECs was significantly higher than those produced in the control and CM groups (p<0.05). Conclusion: Neither the presence of oviductal epithelial cells nor their conditioned medium could improve the developmental potential of ovine embryos during IVF. Moreover, no relationship was observed between the relative abundance of Zar1 transcript in zygotes produced in different conditions and the corresponding subsequent embryonic development.