Changes in thecal and granulosa cell LH and FSH receptor content associated with follicular fluid and peripheral plasma gonadotrophin and steroid hormone concentrations in preovulatory follicles of mares.
Abstract: Individual antral follicles from 11 horse mares were studied at three stages of the oestrous cycle to determine the characteristics of the presumptive ovulatory follicle. Mares were ovariectomized (ovex) during the late luteal phase on Day 14 after ovulation (Group 1) and on the 1st (Group 2) or 4th (Group 3) day of oestrus. Every follicle greater than 5 mm in diameter was dissected from each ovary; follicles greater than or equal to 15 mm in diameter were analysed separately while others were pooled by size for subsequent analyses. The presumptive ovulatory follicle possessed the following characteristics: in Groups 2 and 3 they were the largest in size; in all groups they contained the largest amount of protein in the granulosa cell component; they were the most vascular; they contained the highest follicular fluid oestradiol concentration; and they possessed the highest granulosa cell LH/hCG receptor content. In 9 mares, there was one such follicle present. In 2 mares, there were 2 such follicles present and one of these mares had a history of repeated double ovulations. The presumptive ovulatory follicle of Group 1 mares contained more thecal LH receptor than did non-ovulatory follicles. There were no differences in granulosa FSH receptor content amongst follicles, although smaller follicles tended to have increased FSH receptor content. Follicular fluid FSH and LH reflected peripheral hormone concentrations with follicular fluid LH being highest in presumptive ovulatory follicles of Group 3 mares. Follicular fluid progesterone concentrations tended to be higher in presumptive ovulatory follicles when compared with small follicles. Within a class of follicle, follicular fluid androstenedione and testosterone concentrations were lower in follicles of Group 1 mares than in follicles from Group 2 and 3 mares, reflecting endogenous stimulation of androgen biosynthesis by LH. Elevated follicular-fluid oestradiol occurred only in the presumptive ovulatory follicle with concentrations at least 30-50-fold higher than in non-ovulatory follicles. These results demonstrate that the presumptive ovulatory follicle in horse mares has been selected by at least Day 14 after ovulation and can be identified at this time by its various biochemical characteristics. Only after the first day of oestrus were physical characteristics such as size accurately able to predict ovulatory follicle status. These results clearly demonstrate the relationship between LH stimulation of androgen biosynthesis in vivo regardless of follicle size or status (ovulatory or non-ovulatory).(ABSTRACT TRUNCATED AT 400 WORDS)
Publication Date: 1987-01-01 PubMed ID: 3119827
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The research investigates the characteristics of preovulatory follicles at three stages of the oestrous cycle in horse mares. It establishes a correlation between the largest follicle and ovulation, and identifies the biochemical characteristics necessary for predicting ovulatory follicle status.
Research Methodology
- The research involves an experimental study on individual antral follicles from 11 horse mares during three stages of the oestrous cycle.
- The mares were ovariectomized during the late luteal phase on Day 14 after ovulation (Group 1), on the 1st (Group 2), or the 4th day of oestrus (Group 3).
- All follicles greater than 5 mm in diameter were dissected from each ovary. Larger follicles (greater than or equal to 15 mm) were analyzed separately, and others were grouped by size for further analysis.
Key Findings
- The researchers defined presumptive ovulatory follicle as the one possessing several characteristics: It was the largest follicle in Groups 2 and 3, contained the largest amount of protein, was the most vascular, had the highest follicular fluid oestradiol concentration, and contained the most granulosa cell LH/hCG receptor content.
- The presumptive ovulatory follicle in Group 1 mares contained more thecal LH receptor than non-ovulatory follicles.
- There was no difference in granulosa FSH receptor content among the follicles, but smaller follicles had slightly more FSH receptor content.
- The highest follicular fluid oestradiol levels were found in the presumptive ovulatory follicle, with concentrations 30-50 times higher than in non-ovulatory follicles.
Conclusion
- The results of the study suggest that the presumptive ovulatory follicle is selected by Day 14 after ovulation and can be identified through their biochemical characteristics. Physical characteristics like size, by contrast, accurately predict ovulatory follicle status only after the first day of oestrus.
- This research further demonstrates the relationship between LH stimulation of androgen biosynthesis in vivo, regardless of the follicle’s size or status (whether ovulatory or non-ovulatory).
Cite This Article
APA
Fay JE, Douglas RH.
(1987).
Changes in thecal and granulosa cell LH and FSH receptor content associated with follicular fluid and peripheral plasma gonadotrophin and steroid hormone concentrations in preovulatory follicles of mares.
J Reprod Fertil Suppl, 35, 169-181.
Publication
Researcher Affiliations
- Department of Veterinary Science, University of Kentucky, Lexington 40546-0076.
MeSH Terms
- Androstenedione / analysis
- Animals
- Estradiol / analysis
- Female
- Follicle Stimulating Hormone / analysis
- Follicular Phase
- Gonadal Steroid Hormones / analysis
- Granulosa Cells / analysis
- Horses / metabolism
- Luteinizing Hormone / analysis
- Ovarian Follicle / anatomy & histology
- Progesterone / analysis
- Receptors, FSH / analysis
- Receptors, LH / analysis
- Testosterone / analysis
- Theca Cells / analysis
Citations
This article has been cited 2 times.- Ishak GM, Bashir ST, Dutra GA, Gastal GDA, Gastal MO, Cavinder CA, Feugang JM, Gastal EL. In vivo antral follicle wall biopsy: a new research technique to study ovarian function at the cellular and molecular levels. Reprod Biol Endocrinol 2018 Jul 28;16(1):71.
- Dell'Aquila ME, Caillaud M, Maritato F, Martoriati A, Gérard N, Aiudi G, Minoia P, Goudet G. Cumulus expansion, nuclear maturation and connexin 43, cyclooxygenase-2 and FSH receptor mRNA expression in equine cumulus-oocyte complexes cultured in vitro in the presence of FSH and precursors for hyaluronic acid synthesis. Reprod Biol Endocrinol 2004 Jun 22;2:44.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
