Reproductive Hormones

Reproductive Hormones

These hormones are secreated from Hypothalamus, Anterior Pituitary, Posterior Pituitary, Ovary, Testis and Uterus. According to the chemical structure, the reproductive hormones can be divided into two classes: Class one: Include the Protein, Peptide, Polypeptide hormones. Class two: Include the Steroid and lipid hormons.

Reproductive Hormones

Gland
Hormone
Chemical Class
Function
Hypothalamus
Gonadotropin releasing h. GnRH
Peptide
FSH and LH release
Prolactin releasing factor PRF
Peptide
Prolactin release

Reproductive Hormones

Gland
Hormone
Chemical Class
Function
Hypothalamus
Prolactin inhibiting factor PIF
Peptide
Prolactin retention
Corticotropin releasing h. CRH
Peptide
ACTH release

Reproductive Hormones

Gland
Hormone
Chemical Class
Function
Anterior Pituitary
Follicle Stimulating h. FSH
Protein
1. Follicle growth 2. Estrogen release 3. Spermatogenesis
Luteinizing h. LH
Protein
1. Ovulation 2. Corpus luteum formation and function 3. Testosterone release

Reproductive Hormones

Gland
Hormone
Chemical Class
Function
Anterior Pituitary
Prolactin
Protein
Milk synthesis
Adrenocotiotropin ACTH
Poly-peptide
Release of glucocorticoid

Reproductive Hormones

Gland
Hormone
Chemical Class
Function
Posterior Pituitary
Oxytocin
Peptide
1. Parturition 2. Milkejection

Reproductive Hormones

Gland
Hormone
Chemical Class
Funktion
Ovary
Estrogens (Estradiol)
Steroid
1. Female sexual behavior 2. Secondary sex characteristics 3. Maintenence of female duct system 4. Mamary growth

Reproductive Hormones

Gland
Hormone
Chemical Class
Funktion
Ovary
Progestins (Progesterone)
Steroid
1. Maintenance of pregnancy 2. Mamary growth
Relaxin
Polypeptide
1. Expantion of pelvis2. Dilation of cervix
Inhibin
Protein
Prevent release of FSH

Reproductive Hormones

Gland
Hormone
Chemical Class
Funktion
Testis
Androgens (Testosterone)
Steroid
1. Male sexual behavior 2. Spermatogenesis 3. Mantenance of male duct system 4. Function of accessory glands
Inhibin
Protein
Prevent release of FSH

Reproductive Hormones

Gland
Hormone
Chemical Class
Function
Uterus
Prostaglandin F2α (PGF2α) Lipid
Regression of corpus luteum 2. Parturition

Hormonal Regulation of Reproduction in the female animal

Hormonal Regulation of Reproduction in the female animal
The CNS receives information from the environment of the animal (external signals: visual, olfactory, auditory, and tactile) and conveys this information to the gonads through the Hypothalamo-Pituitary-Gonadal axis.

Hormonal Regulation of Reproduction in the female animal

In the hypothalamus, endocrine neurons produce Gonadotrophin Releasing Hormone (GnRH).

Hormonal Regulation of Reproduction in the female animal

This GnRH is transported via the hypothalamo-hypophyseal portal system to the anterior lobe of the pituitary gland.


Hormonal Regulation of Reproduction in the female animal
Here it stimulates the gonadotroph cells of the pituitary gland to secrete Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH).

Hormonal Regulation of Reproduction in the female animal

FSH stimulates the development of ovarian follicles.

Hormonal Regulation of Reproduction in the female animal

LH stimulates the theca interna of the follicle to synthesis of androstenedione from cholesterol. Androstenedione is converted into testosterone.

Hormonal Regulation of Reproduction in the female animal

In the granulosa cells of the follicle the testosterone is aromatised to oestradiol-17β under the influence of FSH.

Hormonal Regulation of Reproduction in the female animal

At the same time, the granulosa cells also produce inhibin. Inhibin has a negative feedback on the FSH release from the pituitary gland, thus controlling follicle development.

Hormonal Regulation of Reproduction in the female animal

The high level of LH initiates the ovulation. After ovulation the remnants of the follicle are converted into the corpus luteum under the influence of LH.


Hormonal Regulation of Reproduction in the female animal
The corpus luteum produce the progesterone. Progesterone is essential for: the normal cycle in the cow the maintenance of pregnancy.

Hormonal Regulation of Reproduction in the female animal

It prepares the endometrium for the implantation of the embryo, and inhibits the contractions of the uterine wall.

Hormonal Regulation of Reproduction in the female animal

Progesterone has a negative feedback on the hypothalamus, thus decreases the secretion of GnRH, and therefore inhibits new ovulations.

Hormonal Regulation of Reproduction in the female animal

If the pregnancy is not occur, and at around day 16 after ovulation, the endometrium of the non pregnant uterus will release prostaglandin F2α.

Hormonal Regulation of Reproduction in the female animal

Prostaglandin F2α is luteolytic, which means that it initiates the regression of the corpus luteum.

Hormonal Regulation of Reproduction in the female animal

As a result of the regression of the corpus luteum, progesterone concentrations in the blood will decrease, and the progesterone block on the GnRH release from the hypothalamus disappears.

Hormonal Regulation of Reproduction in the female animal

This initiates a new follicular phase.