Delayed follicular development and ovulation following inhibition of FSH with equine follicular fluid in the mare.

The research article examines the effect of follicular fluid, obtained from horses, on the follicular development and ovulation process. Two experiments were conducted where the fluid was administered to mares, and revealed that a proteinaceous substance in the fluid suppressed the concentration of Follicle Stimulating Hormone (FSH), leading to delayed follicular growth and ovulation.

Manner of experiments

In the study, two experiments were carried out where mares were injected with PGF(2alpha) on Day 10 (with ovulation assumed to be on Day 0). In the first experiment, whole equine follicular fluid was administered into the mares twice daily from Day 10 to Day 14. The second experiment mirrored the first, but the follicular fluid was filtered through charcoal to remove steroids.

• The FSH levels were monitored and analyzed from Days 10 to 21 for both experiments.
• The study also inspected the diameter of the largest follicle from Day 10 to Day 18 in the mares.

Key Findings

Analysis of both experiments revealed the following:

• The administration of pure follicular fluid did have an impact on the quantity of FSH, leading to an increase in FSH concentrations between Days 15 and 17.
• Surprisingly, the charcoal-filtered fluid also caused a rise in FSH concentrations during the same time period.
• The treatment with both types of follicular fluid resulted in an inhibition of follicular growth by Day 14 (with pure fluid) and by Day 15 (with charcoal-filtered fluid).
• The interval between each ovulation was found to be longer in the treated groups than in the control groups.

Conclusions

The study concluded that equine follicular fluid contains a proteinaceous substance that suppresses the circulating concentration of FSH hormone. The decline in FSH levels would then subsequently lead to inhibited follicular growth and delayed ovulation.