Development to blastocysts of one- to two-cell equine embryos after coculture with uterine tubal epithelial cells.

This research study investigates the development of one- to two-cell horse embryos in the presence or absence of uterine tubal epithelial cells (UTEC). The findings suggest that co-culturing with UTEC significantly enhances the development of the embryos into blastocysts, compared to culture without UTEC, but these embryos mature at a lesser rate compared to four- to eight-cell embryos also co-cultured with UTEC.

Research Methodology

• The research involved studying the development of one- to two-cell embryos which were fertilized in vivo (inside the body). These embryos were either cultured with uterine tubal epithelial cells (UTEC) or without them.
• The researchers collected 26 one- to two-cell embryos surgically from the uterine tubes of pony mares one day after ovulation. They also collected nine four- to eight-cell embryos two days after ovulation.
• Some presumptive zygotes and two-cell embryos were co-cultured with UTEC (17 specimens) while some were cultured without UTEC (9 specimens). All four- to eight-cell embryos were co-cultured with UTEC as positive controls.
• The UTECs used were in cell suspensions utilized within two weeks after starting the cultures. The embryos were cultured until they turned into blastocysts or showed signs of morphologic degeneration.

Research Findings

• Out of the specimens, six presumptive zygotes did not cleave in vitro (in a controlled environment).
• The rate of development into blastocysts of one-cell (4 of 11) and two-cell (2 of 6) embryos co-cultured with UTEC was found to be similar.
• Co-culturing one- to two-cell embryos with UTEC significantly improved their development into blastocysts, compared to their development in medium alone (35% vs 0%, respectively).
• The development of one- to two-cell embryos into blastocysts was less when co-cultured with UTEC as compared to the development of four- to eight-cell embryos also co-cultured with UTEC (35% vs 89%, respectively).

Conclusion

• Overall, this study reveals that co-culturing one- to two-cell horse embryos with UTEC drastically improves their development into blastocysts.
• However, there was a lower rate of development into blastocysts when these embryos were compared with four- to eight-cell embryos, which were also co-cultured with UTEC.