Characterization of plasma progesterone concentrations for two distinct luteal morphologies in mares.
Abstract: Plasma progesterone concentrations in mares were determined in two experiments during the time that the luteal glands were detectable by transrectal ultrasonography. In both experiments, corpora lutea were classified into two types of morphologies based on their ultrasonic appearance: centrally nonechogenic luteal glands (fluid-filled) and uniformly echogenic luteal glands (non-fluid-filled). In Experiment 1, daily blood samples were taken from horse mares during August through October and May through July. There were no significant effects of season or luteal morphology on progesterone concentration. There was a significant main effect of day, but no day-by-season or day-by-morphology interactions. Progesterone increased significantly between Days 1 and 3 (mean progesterone concentration, 2.5 vs 5.2 ng/ml, respectively), between Days 3 and 4 (5.2 vs 7.8 ng/ml), and between Days 4 and 5 (7.8 vs 11.0 ng/ml). Progesterone did not decrease significantly until between Days 11 and 15 (11.6 and 6.1 ng/ml). Subsequent decreases occurred between Days 15 and 16 (6.1 vs 3.9 ng/ml), and Days 16 and 17 (3.9 vs 2.5 ng/ml). In Experiment 2, blood samples were obtained from pony mares at 1 2-h intervals for 3 h before and 2 h after the defined onset of luteal development (end of evacuation of the ovulatory follicle). Additional blood samples were taken at 5, 8 and 12 h after the onset of luteal development, and thereafter at 12-h intervals for 5d. There were no significant differences between centrally nonechogenic luteal glands (n=7) and uniformly echogenic luteal glands (n=5) during the first 5 d of luteal development. There was no time-by-morphology interaction, but there was a significant time effect. The first significant increase in progesterone concentration occurred between Hours 12 and 24 (0.5 vs 1.1 ng/ml). Additional increases were detected between Hours 24 and 36 (1.1 vs 2.6 ng/ml), Hours 36 and 48 (2.6 vs 4.3 ng/ml), Hours 48 and 60 (4.3 vs 6.1 ng/ml), Hours 60 and 72 (6.1 vs 9.4 ng/ml), and Hours 72 and 96 (9.4 vs 13.8 ng/ml). The hypothesis was supported that fluid-filled corpora lutea do not differ from non-fluid-filled corpora lutea with regard to progesterone production.
Publication Date: 1989-08-01 PubMed ID: 16726666DOI: 10.1016/0093-691x(89)90310-5Google Scholar: Lookup
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- Journal Article
Summary
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This research investigates the hormone progesterone levels in mares under different conditions, with results indicating no significant difference based on the luteal morphology in the mares’ ovaries, which can be fluid-filled (centrally nonechogenic) or non-fluid-filled (uniformly echogenic).
Objective and Method
- The objective of the research was to determine plasma progesterone concentrations in mares during the presence of luteal glands, and compare the amounts between two different types of luteal morphologies. The glands were observed through a transrectal ultrasound.
- The corpora lutea in the ovaries were classified into two categories, based on ultrasonic appearances: centrally nonechogenic, or fluid-filled, and uniformly echogenic, or non-fluid-filled.
- The research was conducted over two experiments, where blood samples were collected at different intervals, and during different times of the year.
Results from Experiment 1
- In Experiment 1, daily blood samples were collected from horse mares between August and October, and May and July. The analyses revealed no significant difference in progesterone concentration due to the season or the type of luteal morphology.
- The progesterone concentrations did vary significantly by day, with substantial increases noted between specific days, though there was no consistent interaction of day with season or luteal morphology.
Results from Experiment 2
- In Experiment 2, blood samples were obtained before and after the onset of luteal development in pony mares and continued to be taken over the course of five days.
- Much like Experiment 1, there was no significant difference between the progesterone levels in mares with fluid-filled corpora lutea and those with non-fluid-filled glands, nor was there a time-by-morphology interaction.
- However, a significant time effect was noted with progesterone levels increasing significantly across certain hourly intervals.
Concluding Remarks
- The findings supported the hypothesis that fluid-filled corpora lutea do not differ from non-fluid-filled corpora lutea in regards to progesterone production.
- This indicates that regardless of the different types of luteal morphologies, the plasma progesterone concentrations in mares aren’t significantly affected.
Cite This Article
APA
Townson DH, Pierson RA, Ginther OJ.
(1989).
Characterization of plasma progesterone concentrations for two distinct luteal morphologies in mares.
Theriogenology, 32(2), 197-204.
https://doi.org/10.1016/0093-691x(89)90310-5 Publication
Researcher Affiliations
- Department of Veterinary Science, University of Wisconsin-Madison, 1655 Linden Drive Madison, WI 53706, USA.
Citations
This article has been cited 7 times.- Newcombe JR, Wilsher S, Cuervo-Arango J. The post-ovulatory rise in progesterone is lower and the persistence of oestrous behaviour longer during the first compared with the second cycle of the breeding season in mares. Reprod Domest Anim 2023 Jan;58(1):141-145.
- Takahashi Y, Akai M, Murase H, Nambo Y. Seasonal changes in serum progesterone levels in Thoroughbred racehorses in training. J Equine Sci 2015;26(4):135-9.
- Rusnell BJ, Pierson RA, Singh J, Adams GP, Eramian MG. Level set segmentation of bovine corpora lutea in ex situ ovarian ultrasound images. Reprod Biol Endocrinol 2008 Aug 4;6:33.
- Relave F, Lefebvre RC, Beaudoin S, Price C. Accuracy of a rapid enzyme-linked immunosorbent assay to measure progesterone in mares. Can Vet J 2007 Aug;48(8):823-6.
- Baerwald AR, Adams GP, Pierson RA. Form and function of the corpus luteum during the human menstrual cycle. Ultrasound Obstet Gynecol 2005 May;25(5):498-507.
- Giguère S, Vaillancourt D. Evaluation of two qualitative enzyme immunoassays for the rapid assessment of progesterone in equine plasma. Can Vet J 1994 Oct;35(10):643-5.
- Scarlet D, Schuler G, Malama E, Bollwein H, Bocci C, Colleoni S, Lazzari G, Galli C, Kowalewski MP. Endocrine profile and OPU-ICSI outcomes in mares: a comparative study. Reprod Fertil 2025 Jul 1;6(3).
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