Modulation of oviductal transport in mares by local application of prostaglandin E2.

This research examines the effect of applying prostaglandin E2 locally to enhance the transport of embryos in the oviducts of mares. The study found that single local application of prostaglandin E2 facilitates the faster transport of embryos.

Objective of the Study

• The research primarily aimed to study the influence of a single local application of prostaglandin E2 (PGE2) on the transport of embryos within the oviduct of mares. PGE2 is believed to relax the smooth muscle of the isthmus, a section of the female reproductive tract, to help progress the embryos to the uterus.

Methodology

• A total of 22 Thoroughbred and Pony mares were inseminated during oestrus (the time in the reproductive cycle when horses are sexually receptive) on alternate days.
• On day 4 post-ovulation, part of the female reproductive tract was examined using flank laparoscopy. One group of mares received an application of a commercial preparation of PGE2 in a gel, while the control group splashed with a gel without PGE2.
• The uterus of each mare was flushed on day 5 with phosphate-buffered saline and 1% fetal bovine serum. If no embryo was recovered on day 5, the process was repeated on days 7 or 8.

Findings

• The rate of embryo recovery was comparable between the PGE2-treated group and the control group. However, on day 5, the embryo recovery was significantly higher from the PGE2-treated mares compared to the control group, indicating that PGE2 application increased the rate of embryo transport.
• Additionally, unfertilized oocytes were found only in the PGE2-treated mares on day 5, not in the control group.
• Embryos recovered on day 5 were compacted morulae (an early-stage embryo), while those recovered on days 7 or 8 were expanding blastocysts (a later stage of embryonic development).

Implications

• The research supported the belief that embryonic PGE2 facilitates the transport of embryos in the oviducts of mares.
• The findings suggest that a single local application of PGE2 could be a practical method to accelerate the passage of embryos through the oviduct, making non-surgical recovery of morulae from the uterus possible.