Related Experiment Video
Updated: Jul 6, 2026
09:30
In Vitro Culture Strategy for Oocytes from Early Antral Follicle in Cattle
Published on: July 8, 2020
Ovarian function in Nelore (Bos taurus indicus) cows after post-ovulation hormonal treatments
R Machado1, M A C M Bergamaschi, R T Barbosa
1Embrapa Pecuária Sudeste, São Carlos, SP, Brazil.
Theriogenology
|March 14, 2008
Summary
Strategies to enhance early pregnancy recognition in cows were tested. Human chorionic gonadotropin (hCG) improved luteal function, while estradiol-17beta altered follicular dynamics but hastened luteolysis, failing to extend corpus luteum lifespan.
Area of Science:
- Reproductive biology
- Endocrinology
- Veterinary science
Background:
- Maternal recognition of pregnancy in cows necessitates blocking luteolysis via conceptus signaling.
- Optimal uterine environment for conceptus development relies on progesterone regulated by the corpus luteum (CL).
Purpose of the Study:
- To evaluate strategies for optimizing luteal function and preventing dominant follicle-induced luteolysis in Nelore beef cows.
- To investigate the effects of hCG and estradiol-17beta on CL lifespan and progesterone production.
Main Methods:
- Forty Nelore cows underwent a GnRH/PGF(2alpha)/GnRH protocol.
- Cows received hCG, estradiol-17beta, or both, or no treatment, after ovulation (Day 0).
- Ovarian ultrasonography, plasma progesterone, and estrus were monitored daily.
Main Results:
- Human chorionic gonadotropin (hCG) treatment increased accessory CL formation, CL volume, and plasma progesterone (P<0.01).
- Estradiol-17beta induced follicular atresia and new follicular wave emergence, but hastened luteolysis.
- Neither treatment extended the lifespan of the CL in Nelore cows.
Conclusions:
- hCG enhances luteal function and progesterone levels in early luteal phase.
- Estradiol-17beta influences follicular dynamics and accelerates luteolysis, hindering pregnancy maintenance.
- Current strategies are insufficient to extend CL lifespan for successful pregnancy recognition in this model.
Related Concept Videos
01:30Hormonal Control of the Ovarian Cycle
The ovarian cycle is meticulously regulated by the hypothalamic-pituitary-gonadal axis. This cycle orchestrates the release of a mature oocyte, essential for reproduction.
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle. At puberty, GnRH secretion increases in both frequency and...
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle. At puberty, GnRH secretion increases in both frequency and...
01:27Ovarian Cycle
The menstrual cycle includes a critical component known as the ovarian cycle, which undergoes two main phases each month—the follicular phase and the luteal phase. The follicular phase is variable and averaging around 14 days. Ovulation, triggered by a surge in luteinizing hormone (LH), marks the transition between the two phases. The second phase, the luteal phase, is relatively consistent, lasting approximately 14 days, and is marked by the activity of the corpus luteum. While a cycle length...
01:22Hormonal Regulation of the Menstrual Cycle
The ovarian cycle regulates endometrial changes throughout a single menstrual cycle via the coordinated action of gonadotrophin-releasing hormone (GnRH) and gonadotrophins.
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH release.
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH release.