Hormonal inter-relationships throughout the oestrus cycle

 The hormonal inter-relationships throughout the oestrus cycle are regulated by steroid and inhibin feedback mechanisms, originating from the ovary. 

 The hypothalamus governs the secretion of FSH and LH from the pituitary through patterns of secretion of GnRH. Secretion of LH and FSH in turn control the functional status of the gonad. Conversely, the hypothalamus and pituitary response to changes in ovarian steroids and inhibin secretion, either by increasing or decreasing GnRH supply to the pituitary to regulate the secretion of both LH and FSH. This ability of the hypothalamus and pituitary to respond to the functional status of the ovary is referred as a feedback mechanism, and can be either be negative or positive in effect.

NOTES:

 a. GnRH from the hypothalamus stimulates the release of FSH and LH from the adenohypophysis.

b. FSH stimulates production of oestradiol and inhibin by granulosa cells in  the ovarian follicles.

c. Inhibin selectively prevents release of a FSH.

d. When progesterone concentration is low, concentration of oestradiol stimulates a greater surge  of GnRH, FSH and LH via a positive feedback control.

e. LH stimulates production and release of progesterone by granulosa cells in the corpus luteum.

f. High concentration of progesterone inhibit the release of GnRH, FSH and LH, this is a