FSH is a hormone secreted by the pituitary gland in the brain.
FSH stimulates the follicles in the ovaries to ripen several eggs. A follicle is a balloon shaped structure which is filled with fluid and contains an egg, FSH also stimulates the ovaries to produce oestrogen.
The Pre-Ovulatory Phase is the phase between bleeding and ovulation and tends to be more variable than the second half of the menstrual cycle. Although about 20 follicles begin developing each menstrual cycle due to FSH release only one follicle reaches full maturity. As the follicles develop they release oestrogen, which in turn feedbacks to the brain and causes the pituitary gland to cease the production of FSH. The follicle that has matured the most – survives and continues to grow until it is ready for ovulation. The other less mature follicles stop growing (and some even die).
In men, the Follicle Stimulating Hormones initiates sperm production.
Luteinising Hormone is secreted by the pituitary gland to stimulate ovulation that is, the release of the egg or ovum from the follicles.
FSH also readies the mammary glands for milk production.