Menstruation and Menstrual Cycle

At about the age of 10 to 13 years, the ovaries of females are stimulated by the follicle stimulating hormone (FSH) of the pituitary. This is called the onset of puberty and is accompanied by release of hormones oestrogen and progesterone. These hormones control the production of ova or eggs and appearance of secondary sexual characteristics. Unlike males where sperms can be produced through out the life of man, in females the reproductive phase only lasts till the age of 45-50 years. This phase is characterised by the presence of menstrual cycle. Each menstrual cycle typically lasts for 28 days. Thus it occurs every month.