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The ovaries are a key part of the normal development and reproductive function of women. Ovaries are a pair of glands approximately the size and shape of an almond in the female reproductive system where eggs are stored and estrogen is manufactured. They are held in place by several ligaments on either side of the uterus.
Eggs are transported from the ovaries to the uterus via the fallopian tubes. Surrounding the entrance to the fallopian tubes are tiny fimbriae, or fingerlike projections, which guide the egg into the tube each month.
During the childbearing years, approximately — eggs will develop and be released during ovulation. After menopause , the ovaries will stop producing eggs and atrophy shrink. Due to a loss of ovarian functioning and loss of estrogen production, postmenopausal people commonly experience symptoms like hot flashes and vaginal dryness.
Estrogen deficiency also increases your risk of developing osteoporosis, which increases your risk of bone fracture. While cycles may be irregular in the beginning, they will eventually become more regular, with the start of one period being about 28 days from the start of the next.
Each month, approximately 10—12 egg follicles will begin to develop. One will continue to produce a mature egg. The rest will be reabsorbed into the ovarian tissue. About 14 days into the menstrual cycle, that mature egg will be released in a process called ovulation. After ovulation occurs, the empty follicle is known as a corpus luteum.
It will produce progesterone and other hormones crucial for pregnancy for about 14 days. Progesterone helps prepare and thicken the lining of the uterus for implantation if fertilization of the egg with sperm occurs.
Also, if fertilization does occur, this hormonal support will continue throughout pregnancy to prevent other eggs from maturing. If fertilization does not occur, progesterone levels will decline, the corpus luteum will degenerate, and menstruation will begin. The ovaries are sensitive to the effects and changes of the endocrine, or hormonal, system. They respond to and produce their own hormones as needed by the body. In fact, the second major role of the ovary is to secrete the sex hormones—estrogen, progesterone, and very small amounts of androgens, which cause the typical female sex characteristics to develop and be maintained.
Progesterone is also key to reproduction more on that later. Relaxin loosens the pelvic ligaments so they can stretch during labor. Inhibin prevents the pituitary gland from producing hormones.
Third, ovaries release one egg, or sometimes more, each menstrual cycle. This process is called ovulation. Inside each ovary, there are follicles and inside of each follicle is a dormant egg. When a female is born, she has around , to , follicles in her ovaries. By the time she is sexually mature, the female will have around 34, follicles, according to the Encyclopedia Britannica. When a particular egg is stimulated to maturity by hormones released from the pituitary gland, the follicle migrates to the ovary wall.
Here, the egg and the follicle grow and mature. When mature, they are ready for ovulation. Mature follicles, called Graafian follicles, can grow up to about 1. The follicle with the mature egg ruptures, releasing the egg into the nearest fallopian tube.
From there, the egg travels to the uterus. The body produces the hormone progesterone to make the lining of the uterus thicker to be receptive to the incoming egg. This hormone is made by new cells growing where the old egg once was in the ovary. As the eggs mature, the cells in the follicle rapidly divide and the follicle becomes progressively larger. Many follicles lose the ability to function during this process, which can take several months, but one dominates in each menstrual cycle and the egg it contains is released at ovulation.
As the follicles develop, they produce the hormone oestrogen. Once the egg has been released at ovulation, the empty follicle that is left in the ovary is called the corpus luteum. This then releases the hormones progesterone in a higher amount and oestrogen in a lower amount.
These hormones prepare the lining of the uterus for potential pregnancy in the event of the released egg being fertilised. If the released egg is not fertilised and pregnancy does not occur during a menstrual cycle, the corpus luteum breaks down and the secretion of oestrogen and progesterone stops. Because these hormones are no longer present, the lining of the womb starts to fall away and is removed from the body through menstruation. After menstruation, another cycle begins.
The menopause refers to the ending of a woman's reproductive years following her last menstruation. This is caused by the loss of all the remaining follicles in the ovary that contain eggs. When there are no more follicles or eggs, the ovary no longer secretes the hormones oestrogen and progesterone, which regulate the menstrual cycle. As a result, menstruation ceases.
The major hormones secreted by the ovaries are oestrogen and progesterone, both important hormones in the menstrual cycle. Oestrogen production dominates in the first half of the menstrual cycle before ovulation, and progesterone production dominates during the second half of the menstrual cycle when the corpus luteum has formed. Both hormones are important in preparing the lining of the womb for pregnancy and the implantation of a fertilised egg, or embryo.
If conception occurs during any one menstrual cycle, the corpus luteum does not lose its ability to function and continues to secrete oestrogen and progesterone, allowing the embryo to implant in the lining of the womb and form a placenta. At this point, development of the foetus begins. Any medical conditions that stop the ovaries functioning properly can decrease a woman's fertility.
The ovaries naturally stop functioning at the time of menopause.
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