hey visit
http://msnbcmedia.msn.com/i/msnbc/Components/Interactives/Health/WomensHealth/zFlashAssets/menstrual_cycle_dw2[1].swf
read my explanation but plz visit the site
Each cycle takes about 28days
- At the start of each cycle, menstruation occurs-the lining of the uterus breaks down due to a drop in the levels of progesterone, and the cells and blood making up the lining are shed via the vagina. This is menstruation
- Under the influence of oestrogen from the ovaries, the uterus lining then starts to build up again, developing a mass of blood vessels so it is ready to receive a fertilised ovum
-Follicle stimulating hormone(FSH) causes a follicle in one of the ovaries to mature into an ovum.
-About halfway through the cycle, the level of oestrogen drops and there is secretion of LH(luteinizing hormone) from the pituitary gland, triggering ovulation. This is when the wall of the ovary ruptures and an ovum is released
-The remains of the follicle (called corpus luteum) starts to secrete progesterone, which maintains the uterus lining.
-Towards the end of the cycle, the corpus luteum breaks down resulting in a drop in secretion of progesterone. The lining of the uterus breaks down again
