Differential influence of ovine oviduct ampullary and isthmic derived epithelial cells on in vitro early embryo development and kinetic

• We evaluate the possible in vitro specialized role of different segment of oviduct.
• We examine sequential coculture system using isthmic derived epithelial cells.
• Isthmic epithelial cells in IVEP as feeder cells would provide the best condition.
• Oviduct segments have different effects on IVEP same as their in vivo counterparts.
• Sequential coculture system has had no beneficial effects.

Several critical physiological procedures occurred in oviduct during early embryo development. It is now well documented that in vivo there exist a great cross talk between early embryos and oviductal epithelial cells. For many years, the use of somatic cells for coculture with embryos has been investigated to improve in vitro embryo production (IVEP). The objectives of this study was to investigate; (i) whether ampullary and isthmic derived epithelial cells have different effects on IVEP, (ii) if by using different segments (2 equal segments) of isthmus in a sequential coculture system (2 × 2 Days culture period) we could improve IVEP outcomes, and (iii) whether the different coculture systems accelerate the kinetics of blastocyst development. Results of the present study confirmed the positive and highly specialized effects of isthmic compared to ampullary derived epithelial cells on in vitro early development of ovine embryos (45.42% ± 4.01 vs. 36.62% ± 4.75 expanded blastocysts, 18.26% ± 1.00 vs. 10.22% ± 2.75 hatched blastocysts). The usage of isthmic derived epithelial cells as feeder cells in a coculture system compare to ampullary led to a significant (P < 0.05) increase in the total cells number of blastocysts (290.88 ± 68.76 vs. 190.22 ± 55.65). The kinetics of blastocyst development showed a significant increase in coculture system by using isthmic epithelial cells as the feeder cells compare to ampullary derived epithelial cells (25.62% ± 3.05 vs. 12.42% ± 1.00 blastocysts at day 6). Our results showed that by using different segments of isthmus in a sequential coculture system as the feeder cells did not improve the IVEP parameters concerning development or kinetic. In conclusion, we found for the first time that oviductal epithelial cells play the highly specialized role in vitro, same as their in vivo counterparts, in terms of development rate and kinetic.