Effect of aspiration of the preovulatory follicle on luteinization, corpus luteum function, and peripheral plasma gonadotropin concentrations in the mare.

The research investigates how the removal of follicular fluid from the preovulatory follicles in horses can influence luteinization, peripheral gonadotropin concentrations, and ovulation of secondary follicles. The study found that removing the fluid led to an earlier rise in progesterone concentrations and had no significant impact on the development of a normal Corpus Luteum.

Objective and Procedure of the Research

• The aim of the study was to understand the effects of in vivo removal of follicular fluid on luteinization, peripheral gonadotropin concentrations, and ovulation of secondary follicles in mares.
• To achieve this, the researchers aspirated the follicular fluid from preovulatory follicles of mares. The follicles were divided into three groups based on their diameter (Group A: 30-34 mm, Group B: 35-39 mm, Group C: 40-44 mm).
• Mares in Group D were control subjects and their preovulatory follicle was not aspirated.

Observations and Findings

• It was observed that mares in Group A experienced a significantly earlier rise in peripheral progesterone concentrations compared to the control group.
• There was no noticeable difference in duration of progesterone secretion or peak progesterone production between groups.
• Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) values were significantly higher for mares in Groups A and B compared to the control group.
• Mares in Group A also tended to have a higher rate of secondary ovulations compared to other groups.

Conclusions

• These findings supported earlier in vitro results that suggested follicular fluid from small- to medium-sized follicles could contain a luteinization inhibitor.
• Moreover, the study revealed that the presence of follicular fluid during the final days of follicular maturation is not essential for the development of a normal Corpus Luteum (CL).