Progesterone production in mares and echographic evaluation of the corpora lutea formed after follicular aspiration.

The research article discusses an investigation into the progesterone production in mares, focusing specifically on the formation of the Corpus luteum (CL) following follicular aspiration. Ultrasounds were used to analyze and group CLs according to size, and then evaluated for function through the measurement of progesterone concentrations. The results showed the presence and functioning of a CL could be reliably indicated through specific ultrasound scores, which correlated with progesterone levels.

Research Methodology

• The investigation involved ultrasound-guided follicular aspiration in 26 Criollo crossbred mares.
• Post-aspiration, the team undertook an ultrasonographic evaluation of the CL, focusing particularly on the one that developed post puncturing of follicles of varying diameters. The sizes were categorized into three groups: 25-29 mm, 30-35 mm, and >35mm.
• The team measured serum progesterone (P(4)) concentrations to ascertain the functionality of the CLs.

Ultrasound Scoring System

• The researchers classified the CLs according to an established echographic score: a score of one represented anechoic tissue, two referred to a poorly defined luteal structure with low echogenicity, and three was assigned to luteal structures showing echogenicity analogous to a luteal structure.

Findings

• Eight days post-aspiration, the proportion of aspirated follicles that developed into a functional CL (judged by P(4) concentrations) was 57.1% for CL sizes ranging from 25-29mm, 75.0% for sizes 30-35mm, and 72.7% for sizes >35mm. No statistically significant difference was observed across the groups.
• The ultrasound scores of the aspirated follicles were found to correlate with serum P(4) concentrations, implying that the echoscores can be used as a reliable measure of functional CL presence post-aspiration.
• Out of 26 aspirations, 18 resulted in luteal functionality as determined through elevated progesterone concentrations. Of these, 94.4% of mares showed an echoscore of two or three, suggesting successful luteinization.
• Eight days post aspiration, high luteal functionality (P(4) > 2.0 ng/ml) was linked to a high CL echoscore (3) in 88.2% of the mares.

Conclusion

• The study concluded that the echoscore system can serve as a viable screening method to identify the presence of a functional CL after follicular aspiration.
• Specifically, an echoscore of three was identified as an efficient and practical confirmation of luteinization.