Aberrant blood flow area and plasma gonadotropin concentrations during the development of dominant-sized transitional anovulatory follicles in mares.
Abstract: Color Doppler transrectal ultrasound was used to evaluate blood flow area in the wall of dominant anovulatory follicles versus ovulatory follicles in mares during the transition between anovulatory and ovulatory seasons. Daily examinations were done in 11 control mares toward the end of the anovulatory season. In 13 separate mares, follicular fluid was collected from 30-mm follicles, and blood flow areas from control mares were used as a basis for designating the sampled follicle as either anovulatory or ovulatory. Blood flow area in the controls ranged from 0.18 to 0.35 cm(2) in six mares on the day of a 30-mm anovulatory follicle and from 0.25 to 0.86 cm(2) in 11 mares on the day of a 30-mm ovulatory follicle; the ranges did not overlap except for one follicle. In the controls, mean blood flow area was lower (P < 0.05) in the anovulatory group than in the ovulatory group for each day beginning with the first Doppler examination at 25 mm. For plasma LH in controls, an effect of follicle group (P < 0.0001) and an interaction (P < 0.0001) of group by day reflected lower (P < 0.05) concentrations in the anovulatory group on Days -6, -2, and 5-8 (Day 0 = 30-mm follicle). For plasma FSH, an interaction (P < 0.0001) reflected higher (P < 0.05) concentrations in the anovulatory group on Days -3 and 1-4. More (P < 0.05) statistically identified FSH surges occurred in the anovulatory group during Days -7 to 8. In the sampled mares, follicular-fluid concentrations of estradiol, free insulin-like growth factor-1, inhibin-A, and vascular endothelial growth factor were lower (P < 0.05) in 30-mm designated anovulatory follicles than in 30-mm designated ovulatory follicles. Results were interpreted as follows: 1) The future anovulatory dominant-sized follicle developed under an LH deficiency, 2) the LH deficiency led to reductions in blood flow area and in concentrations of follicular-fluid factors, and 3) the reduction in follicle production of FSH suppressors resulted in higher plasma FSH concentrations.
Publication Date: 2004-04-14 PubMed ID: 15084481DOI: 10.1095/biolreprod.104.028498Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigated the difference in blood flow area and hormone levels during development of two types of follicles in mares – those that lead to ovulation and those that do not. The findings suggest that the latter type, known as anovulatory follicles, develop under a deficiency in a hormone called luteinizing hormone (LH), leading to less blood flow and different hormone concentrations as compared to ovulatory follicles.
Methodology
- The researchers used color Doppler transrectal ultrasound, a diagnostic imaging technique, to examine blood flow in the wall of the anovulatory and ovulatory follicles in mares during the transitional phase from anovulatory to ovulatory seasons.
- The study involved daily examinations of 11 control mares at the end of the anovulatory season. In another 13 mares, follicular fluid was collected for testing, and the blood flow data from the control group was used to determine if the sampled follicle was anovulatory or ovulatory.
Results
- They found that the average blood flow area in the anovulatory group was lower than in the ovulatory group. The ranges of the blood flow related to anovulatory and ovulatory follicles showed no overlapping except in one case.
- There was a statistically significant difference in plasma LH (luteinizing hormone) concentrations, with the anovulatory group showing lower concentrations on certain days prior to and after the appearance of a 30mm follicle (considered day 0).
- Similar patterns were observed with plasma FSH (follicle-stimulating hormone) levels. However, the anovulatory group had higher FSH concentrations on certain days, and experienced more statistically identified FSH surges during specific days of the study.
- In mares where follicular fluid was collected, anovulatory follicles showed lower concentrations of a number of substances including estradiol, insulin-like growth factor-1, inhibin-A, and vascular endothelial growth factor, as compared to ovulatory follicles.
Conclusion
- Based on these findings, the researchers proposed that anovulatory follicles develop under a deficiency of LH. This deficiency leads to reductions in blood flow area and concentrations of certain substances in the follicular fluid.
- Further, the researchers suggested that a drop in follicle production of FSH suppressors resulted in higher plasma FSH concentrations. Thus, these findings provide deeper insights into the physiological processes involved in follicle development and ovulation in mares.
Cite This Article
APA
Acosta TJ, Beg MA, Ginther OJ.
(2004).
Aberrant blood flow area and plasma gonadotropin concentrations during the development of dominant-sized transitional anovulatory follicles in mares.
Biol Reprod, 71(2), 637-642.
https://doi.org/10.1095/biolreprod.104.028498 Publication
Researcher Affiliations
- Eutheria Foundation, Cross Plains, WI 53528, USA.
MeSH Terms
- Animals
- Anovulation
- Female
- Follicle Stimulating Hormone / blood
- Horses
- Luteinizing Hormone / blood
- Ovarian Follicle / blood supply
- Ovarian Follicle / diagnostic imaging
- Ovarian Follicle / physiology
- Ovulation / physiology
- Regional Blood Flow
- Seasons
- Ultrasonography, Doppler, Color
Citations
This article has been cited 3 times.- Dutra GA, Ishak GM, Pechanova O, Pechan T, Peterson DG, Jacob JCF, Willard ST, Ryan PL, Gastal EL, Feugang JM. Seasonal variation in equine follicular fluid proteome. Reprod Biol Endocrinol 2019 Mar 6;17(1):29.
- Fraser HM. Regulation of the ovarian follicular vasculature. Reprod Biol Endocrinol 2006 Apr 12;4:18.
- Feugang JM, Gad A, Menjivar NG, Ishak GM, Gebremedhn S, Gastal MO, Dlamini NH, Prochazka R, Gastal EL, Tesfaye D. Seasonal influence on miRNA expression dynamics of extracellular vesicles in equine follicular fluid. J Anim Sci Biotechnol 2024 Oct 9;15(1):137.
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