COW REPRODUCTIVE HORMONES

Summary

This video explains the hormonal regulation of gonadal activity in cows, detailing the role of the hypothalamus and adenohypophysis in controlling reproductive processes. It describes how GnRH stimulates FSH and LH production, which in turn regulate follicular growth, ovulation, and the secretion of estrogen. The script highlights how estrogen influences sexual behavior, ovulation, and sperm transport. It further discusses the formation of the corpus luteum, the role of progesterone in maintaining pregnancy, and how luteolysis occurs if pregnancy doesn't happen. The cyclical process of follicular growth and ovulation is also explained.

Takeaways

• 😀 The hypothalamus controls gonadal activity in cows by releasing GnRH (Gonadotrophin releasing hormone).
• 😀 GnRH stimulates the adenohypophysis to release FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone).
• 😀 FSH stimulates the growth and maturation of ovarian follicles.
• 😀 LH triggers the final stages of follicle maturation and ovulation of the dominant follicle.
• 😀 The dominant follicle produces estrogen, specifically estradiol, which is responsible for sexual behavior during estrus.
• 😀 Estradiol stimulates the hypothalamus and pituitary gland to increase GnRH levels, but the response to LH is much stronger.
• 😀 Inhibin, secreted by granulosa cells, inhibits FSH production without affecting LH, helping regulate the cycle.
• 😀 Estrogens also affect the uterus, aiding in sperm transport during estrus.
• 😀 After ovulation, the remnants of the follicle form a clot called Corpus Luteum Hemorrhagic, which later becomes the corpus luteum.
• 😀 The corpus luteum produces progesterone, which negatively feedbacks to reduce GnRH, FSH, and LH levels, preventing new ovulations.
• 😀 Progesterone prepares the uterine lining for embryo implantation and supports early pregnancy.
• 😀 If no pregnancy occurs, PGF2 alpha is released, leading to luteolysis and the formation of the non-functional corpus albicans, restarting the cycle.

Q & A

What is the role of the hypothalamus in controlling gonadal activity in cows?

The hypothalamus, located at the base of the brain, secretes Gonadotrophin Releasing Hormone (GnRH), which stimulates the production and release of FSH and LH from the adenohypophysis (pituitary gland), thereby controlling gonadal activity.

How does FSH influence the ovarian follicles in cows?

Follicle Stimulating Hormone (FSH) stimulates the growth and maturation of ovarian follicles, preparing them for ovulation.

What is the function of LH in the cow's reproductive cycle?

Luteinizing Hormone (LH) triggers the final stage of follicular maturation and causes ovulation of the dominant follicle.

What hormone is primarily responsible for the sexual behavior of cows in heat?

Estradiol, a type of estrogen produced by the dominant follicle, is responsible for expressing sexual behavior in cows, indicating that the cow is ready to conceive.

How do estrogens and inhibin work together to regulate the cow's reproductive cycle?

Estrogens, along with inhibin (secreted by granulosa cells of the growing follicle), help regulate the peak of LH, which leads to ovulation. Inhibin suppresses FSH production without affecting LH levels.

What is the role of progesterone after ovulation in cows?

After ovulation, the corpus luteum (yellow body) produces progesterone, which has a negative feedback effect on the hypothalamus to suppress GnRH, FSH, and LH, preventing further ovulation and preparing the uterus for potential pregnancy.

What happens if pregnancy does not occur after ovulation in cows?

If pregnancy does not occur within 17 days after estrus, the uterus produces PGF2 alpha, which induces luteolysis (destruction of the corpus luteum), decreasing progesterone levels and allowing the hypothalamus to resume GnRH production and restart the reproductive cycle.

What is luteolysis and what role does PGF2 alpha play in this process?

Luteolysis is the regression or destruction of the corpus luteum, and PGF2 alpha is the hormone that triggers this process, leading to a drop in progesterone levels and the initiation of a new reproductive cycle.

What is the corpus albicans and how is it formed?

The corpus albicans is a non-functional white body formed after the regression of the corpus luteum during luteolysis. It results from the breakdown of the corpus luteum, which is triggered by PGF2 alpha.

How does the negative feedback of progesterone regulate the reproductive cycle in cows?

Progesterone, produced by the corpus luteum, negatively feeds back to the hypothalamus to inhibit GnRH production, which decreases FSH and LH levels, preventing further ovulations until pregnancy is either established or the cycle restarts.