FSH – Gonadotropins

Gonadotropins

LH (Luteinizing hormone) & FSH (Follicle stimulating hormone) are released from anterior pituitary.
The placenta produces human Chorionic Gonadotropin (hCG).
FSH and LH are secreted under the effect of Gonadotropin Releasing Hormone (GnRH).
Puberty does not set in until the pulsatile secretion of LHRH is started by hypothalamus.
The fundamental change during puberty is a reduction in hypothalamic inhibition of LHRH release.

FSH is synthesized & secreted by gonadotrophes of the Anterior Pituitary.
FSH regulates the development, growth, pubertal maturation, & reproductive processes of the body.
The FSH stimulates growth of ovarian follicles in females & spermatogenesis (sertoli cells) in males.
The FSH levels are normally low during childhood & in females, high after menopause.
High FSH levels are an indication of subfertility and/or infertility.
Diminished secretion of FSH can result in hypogonadism – typically manifested in males as failure in production of normal number of sperms.
In females, cessation of reproductive cycles is commonly observed.
FSH brings about its action by specific receptor binding and cAMP.

In the females, FSH prepares the Graafian follicle for the action of LH and, enhances the release of estrogen induced by LH.
The FSH secretion rises during the follicular phase of the menstrual cycle. Reaches a peak by the 14th day and starts falling when ovulation occurs.
Ovulation occurs as a result of positive feedback effect of estrogen producing the preovulatory LH surge.
The level of FSH and LH falls during the postovulatory phase, unless fertilization and implantation occur.
The gonadotropin production is under the feedback control by the sex hormones.
High levels of FSH and LH are seen in postmenopausal women due to lack of this feedback.

The conversion of primary into secondary spermatocytes in the seminiferous tubules is stimulated by FSH.
Spermatogenesis cannot proceed without FSH.
FSH needs testosterone for completion of spermatogenesis.
FSH initiates the proliferation process of spermatogenesis, and testosterone is for final maturation of spermatozoa.
Since the testosterone is secreted under the influence of LH, both FSH and LH must be secreted for normal spermatogenesis.

Biochemistry Club, Biochemistry Online courses.