The female reproductive organs are situated in the pelvic cavity and SO are enclosed and protected by the pelvic bones. The ovaries are central to the female reproductive system because they hold all the female ova (eggs). The ovaries release one egg during the process of ovulation, and thww5r021is happens first at puberty. Once released, the egg passes along the Fallopian tube to the uterus (womb) a hollow, muscular organ capable of considerable expansion to accommodate a growing fetus during pregnancy. The neck of the uterus is also known as the cervix, projects into the vagina. The vagina is a muscular organ that is able to expand greatly during sexual intercourse and childbirth.

HORMONES AND THE MENSTRUAL CYCLE

The ovaries produce two hormones – estrogen and progesterone. These two hormones are controlled by the pituitary gland, which produces follicle-stimulating hormone (FSI I) and luteinizing hormone (LII), which regulate the menstrual cycle.

During the first half of the menstrual cycle the pituitary produces FSH, which causes an egg to mature within the ovary in preparation for release. Towards the middle of the cycle, LH levels start to rise and trigger the release of the egg (this usually occurs about 14 days before the onset of menstruation). The hormone progesterone causes the uterine lining to thicken during the second half of the menstrual cycle, in preparation for possible implantation of a fertilized egg, should fertilization take place. Whenever fertilization does not occur, the uterine lining is expelled menstrual bleeding.

When a woman’s ovaries stop responding to the effects of FSH and LH (usually between the ages of 45 and 55), she starts to produce less estrogen and progesterone; this is the of the menopause, when menstruation gradually fades out and fertility ceases.