[Concentrations of anti-Muellerian-hormone in follicular fluid from antral follicles and their relation to functional characteristics of follicle development in mares].

The research investigates the levels of Anti-Muellerian hormone (AMH) in the follicular fluid of mares (female horses) at different stages of follicle development. The findings reveal significant negative correlations between the hormone levels and various factors contributing to follicle growth. The research points to a regulatory role of AMH in equine follicle development and its relevance to controlled superovulation in mares.

Anti-Muellerian Hormone in Follicle Development

• The research is investigating the role of Anti-Muellerian hormone (AMH), which is synthesized by granulosa cells of female mammals and acts as an inhibitor for early follicular recruitment. Primarily, AMH is highly expressed in preantral and small antral follicles.
• The focus is to understand whether AMH also affects the development of large follicles by modifying estrogenesis. The study investigated the concentrations of AMH in equine follicular fluid to determine their relationship to the functional characteristics of follicle development.

Methodology

• The study utilized repeated, transvaginal ultrasound-guided follicle aspirations from 8 mares. This method was chosen to obtain follicular fluids in different stages of development.
• Fluids were gleaned during dioestrus (a phase of the estrous cycle in mares) and from preovulatory follicles following ovulation induced by human chorionic gonadotropin (hCG).

Evaluating Hormone Concentrations

• The concentrations of AMH, estradiol, progesterone, and insulin-like growth factor-1 (IGF-1) were all measured within the follicular fluids obtained.
• Findings revealed significant negative correlations between the intrafollicular concentrations of AMH and estradiol (r = -0.58; p < 0.0001) and between AMH and follicle diameter (r = -0.76; p < 0.001).
• No significant correlation was found between AMH and progesterone or IGF-1, suggesting that the relationship may be primarily between AMH and estradiol/diameter of the follicle.

Implications of the Study

• The study suggests a likely regulatory involvement of AMH in equine follicle development, given the observed dynamic changes of AMH secretion in large antral follicles during the development process.
• Given the species-specific characteristics of equine follicular development, the study’s results are discussed in terms of their potential relevance for controlled superovulation in mares, which could have significant implications for the equine breeding industry.