Ovulationrelease of a mature egg from the female ovary; the release enables the egg to be fertilized by the male sperm cells. Normally, in humansonly one egg is released at one time; occasionally, two or more erupt during the menstrual cycle.
Reproduction is the process by which organisms make more organisms like themselves. But even though the reproductive system is essential to keeping a species alive, unlike other body systems, it's not essential to keeping an individual alive.
The ovaries form part of the female reproductive system. Each woman has two ovaries. They are oval in shape, about four centimetres long and lie on either side of the womb uterus against the wall of the pelvis in a region known as the ovarian fossa. They are held in place by ligaments attached to the womb but are not directly attached to the rest of the female reproductive tract, e. The ovaries have two main reproductive functions in the body. They produce Mature females tube eggs for fertilisation and they produce the reproductive hormones, oestrogen and progesterone.
The function of the ovaries is controlled by gonadotrophin-releasing hormone released from nerve cells in the hypothalamus which send their messages to the pituitary gland to produce luteinising hormone and follicle stimulating hormone. These are carried in the bloodstream to control the menstrual cycle. The ovaries release an egg oocyte at the Mature females tube point of each menstrual cycle. Usually, only a single oocyte from one ovary is released during each menstrual cycle, with each ovary taking an alternate turn in releasing an egg.
Female reproductive system
A female baby Mature females tube born with all the eggs that she will ever have. This is estimated to be around two million, but by the time a girl reaches puberty, this has decreased to abouteggs stored in her ovaries. In the ovary, all eggs are initially enclosed in a single layer of cells known as a follicle, which supports the egg. Over time, these eggs begin to mature so that one is released from the ovary in each menstrual cycle. 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.
Female reproductive organs
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. Mature females tube 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 Mature females tube 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. This occurs in most women around the age of If this happens earlier, before the age of 40, it is called premature ovarian failure or premature ovarian insufficiency. In a polycystic ovary, Mature females tube follicles mature to a certain stage, but then stop growing and fail to release an egg.
These follicles appear as cysts in the ovaries on an ultrasound scan. Any abnormality that causes a loss of normal development of the ovaries, such as Turner syndromecan result in the ovaries not functioning correctly and the loss of a woman's fertility. The ovaries can be damaged by treatments for other conditions, particularly chemotherapy or radiotherapy for cancer treatment. If a woman stops having menstrual periods during her Mature females tube years, this condition is called amenorrhoea.
It can be caused by a of factors. In these cases, fertility can be restored by reducing the intensity of exercise, weight gain and psychological interventions such as cognitive behavioural therapy. Disorders of the pituitary gland can affect normal ovarian function because a lack of the hormones normally released from the pituitary gland will reduce the stimulation of Mature females tube production and the development of follicles in the ovaries. Thyroid overactivity thyrotoxicosis can lead to amenorrhoeaas can any severe illness.
About Contact Events News. Search Search.
More health news + info
You and Your Hormones. Students Teachers Patients Browse.
Human body. Home Glands Ovaries. Ovaries The ovaries produce and release eggs oocytes into the female reproductive tract at the mid-point of each menstrual cycle. They also produce the female hormones oestrogen and progesterone. Alternative names Ovary singular Where are the ovaries? Artwork of the female reproductive system, showing the location of the ovaries. The ovarian phases of a day menstrual cycle.
Ovulation occurs mid-cycle. Related Glands. Related Mature females tube Conditions. Delayed puberty Menopause Polycystic ovary syndrome Turner syndrome Amenorrhoea Thyrotoxicosis Premature ovarian failure Eating disorders Female infertility View all Endocrine conditions. Related Hormones. Related Glossary Supplements.