Estrogen is involved in a feedback mechanism associated with the follicular phase of menstruation. In a negative feedback mechanism, estrogen released from follicles influences the pituitary gland to decrease the production of follicle stimulating hormone, also known as FSH. In a positive feedback mechanism, rising estrogen causes FSH to increase, states About.com.
During the follicular phase of the menstrual cycle, follicle growth is stimulated by FSH. A follicle releases estrogen as it grows larger and prepares to release an egg. As estrogen moves through the bloodstream and back to the pituitary gland it causes a slowdown in the production of FSH in a negative feedback mechanism, according to About.com. One or two of the follicles become dominant and release more estrogen into the bloodstream. High estrogen levels then cause a sudden spike in FSH which is released from the anterior pituitary gland.
A negative feedback mechanism switches to a positive feedback mechanism when the follicle fully matures and the spike in estrogen causes FSH to increase, reports About.com. This last spike in estrogen causes the pituitary gland to suddenly slow FSH production. When this occurs, the ovulatory phase of the menstrual cycle begins.
Luteinizing hormone is also influenced by estrogen and works in conjunction with FSH in reproduction. During a woman?s monthly menstrual cycle, these hormones rise and fall together, reports WebMD.