Growth of small follicles and concentrations of FSH during the equine oestrous cycle.
Abstract: The temporal associations between increases in FSH and growth of small follicles (2-20 mm) were studied during one oestrous cycle (ovulation to ovulation) in 15 horse mares. Follicular diameters were obtained ultrasonically. For each day, follicles were combined for both ovaries, grouped from largest to smallest (excluding dominant follicles), and divided into three to five tiers of six follicles for each mare (for example: tier 1, six largest follicles; tier 2, next six largest follicles). A significant increase in mean diameters followed by a significant decrease was used to define a follicular wave within each of the tiers for each mare. Day of wave emergence was defined by the lowest mean preceding the increase. Follicular waves were detected in all tiers in each mare. The number of detected waves per interovulatory interval was greater (P < 0.05) for tier 5 (2.8 +/- 0.4) than for tier 1 (1.1 +/- 0.1) and tier 2 (1.9 +/- 0.3). A primary follicular wave (wave giving rise to the dominant follicle that ovulated during the subsequent oestrus) was identified in tier 1 in all mares. Composite profiles were constructed by normalizing each tier for each mare to the mean day of emergence of the primary wave for all mares, as detected in tier 1. The composite follicular profiles for the five tiers were approximately parallel; the follicles for tiers 2-5 emerged on the mean day of emergence of the primary wave (6 days after ovulation). The range of follicular means on the common day of wave emergence was 3 mm (tier 5) to 12 mm (tier 1).(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1993-09-01 PubMed ID: 8283426DOI: 10.1530/jrf.0.0990105Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research studied the correlation between the hormone FSH and the expansion of small follicles in horse mares during an oestrous cycle. It was found that growth in smaller follicles followed increases in FSH, creating notable follicular waves, which varied in frequency in different follicle size tiers.
Methodology
- The study observed 15 horse mares throughout one complete oestrous cycle (ovulation to ovulation).
- Follicular diameters were calculated using ultrasound.
- From both ovaries, follicles of a specific day, excluding the dominant follicles, were grouped together from largest to smallest.
- These follicles were further divided into three to five tiers, each comprising six follicles, for each mare.
Follicular Wave Detection
- The research used a significant increase in mean diameters followed by a substantial decrease to define a follicular wave within each of the tiers for every mare.
- The day on which the follicular wave emerged was determined by identifying the lowest mean that came before the increase.
- Follicular waves were noticed in all tiers for every mare in the study.
Findings
- The number of waves detected per interovulatory interval was more significant for the 5th tier (2.8 +/- 0.4) compared to the 1st tier (1.1 +/- 0.1) and the 2nd (1.9 +/- 0.3).
- A primary follicular wave was identified in the 1st tier in all mares. This wave gives birth to the focal follicle which later ovulates during the subsequent oestrus.
Composite Profiles
- Comparative profiles were developed by normalizing each tier for every mare according to the average day of emergence of the primary wave for all mares, as traced in tier 1.
- All five tiers exhibited follicular profiles that were approximately parallel.
- Follicles from tiers 2 through 5 emerged on the average day of emergence of the primary wave (6 days post-ovulation).
- On the day of common wave emergence, the scope of follicular means ranged from 3 mm (for tier 5) to 12 mm (for tier 1).
Cite This Article
APA
Ginther OJ, Bergfelt DR.
(1993).
Growth of small follicles and concentrations of FSH during the equine oestrous cycle.
J Reprod Fertil, 99(1), 105-111.
https://doi.org/10.1530/jrf.0.0990105 Publication
Researcher Affiliations
- Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison 53706.
MeSH Terms
- Animals
- Estrus / physiology
- Female
- Follicle Stimulating Hormone / blood
- Horses / physiology
- Ovarian Follicle / diagnostic imaging
- Ovarian Follicle / physiology
- Ultrasonography
Citations
This article has been cited 1 times.- Martoriati A, Gérard N. Interleukin-1 (IL-1) system gene expression in granulosa cells: kinetics during terminal preovulatory follicle maturation in the mare. Reprod Biol Endocrinol 2003 May 16;1:42.
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