During the fetal stage, which lasts from 9 weeks after fertilization to birth, development continues as cells multiply, move, and change. It gets oxygen and nourishment from the mother's blood via the placenta pluh-SEN-tuh. This disk-like structure sticks to the inner lining of the uterus and connects to the fetus via the umbilical um-BIL-ih-kul cord. The amniotic fluid and membrane cushion the fetus against bumps and jolts to the mother's body.
Pregnancy lasts an average of days — about 9 months. When the baby is ready for birth, its head presses on the cervix, which begins to relax and widen to get ready for the baby to pass into and through the vagina. Mucus has formed a plug in the cervix, which now loosesn. It and amniotic fluid come out through the vagina when the mother's water breaks. When the contractions of labor begin, the walls of the uterus contract as they are stimulated by the pituitary hormone oxytocin ahk-see-TOE-sin.
The contractions cause the cervix to widen and begin to open. After several hours of this widening, the cervix is dilated opened enough for the baby to come through. The baby is pushed out of the uterus, through the cervix, and along the birth canal. The baby's head usually comes first.
The umbilical cord comes out with the baby. It's clamped and cut close to the navel after the baby is delivered. The last stage of the birth process involves the delivery of the placenta, which at that point is called the afterbirth. After it has separated from the inner lining of the uterus, contractions of the uterus push it out, along with its membranes and fluids.
Reviewed by: Larissa Hirsch, MD. Larger text size Large text size Regular text size. What Is Reproduction? What Is the Female Reproductive System? A female's internal reproductive organs are the vagina, uterus, fallopian tubes, and ovaries. The vagina serves three purposes: It's where the penis is inserted during sexual intercourse. It's the pathway the birth canal through which a baby leaves a woman's body during childbirth.
It's the route through which menstrual blood leaves the body during periods. The female reproductive system enables a woman to: produce eggs ova have sexual intercourse protect and nourish a fertilized egg until it is fully developed give birth Sexual reproduction couldn't happen without the sexual organs called the gonads.
According to experts, the actual number of people affected by PCOS may be as high as 1 out of Many cases of PCOS are undiagnosed because the symptoms can vary from person to person and it is often difficult to accurately diagnose it. Because polycystic ovary syndrome can cause significant long-term health consequences, getting an accurate diagnosis and proper treatment is important.
Ovarian cancer is often called the "silent" killer because it usually doesn't cause symptoms until the disease has progressed to an advanced stage. In the U. Fallopian tubes that have been damaged by diseases, infections, or other conditions may be scarred or damaged, which increases the risk of an ectopic tubal pregnancy. Some of the causes of fallopian tube damage include pelvic inflammatory disease PID or endometriosis as well as some sexually transmitted diseases STDs or other pelvic infections.
Normally only one egg is released during ovulation, but it is possible for both ovaries to release an egg at the same time within the same cycle.
If both those eggs become fertilized, they may result in fraternal non-identical twins. Hysterectomy is surgical removal of the uterus. In about half of all hysterectomies, the ovaries are removed as well, in a procedure known as an oophorectomy. This may be recommended to reduce the risk of ovarian cancer, especially if you are considered high risk. Ovarian cysts commonly form during ovulation or pregnancy.
In some cases, they may result from hormonal treatments, including fertility treatments, or endometriosis a condition in which uterine tissue may be found outside the uterus , or as a result of a pelvic infection. This is not usually easy to know.
The simplest way to determine which ovary released the egg is by paying attention to any slight twinges of pelvic pain that may occur during your ovulation window, known as mittelschmerz. That slight pain on the right side or left side is likely the best indicator of which ovary released the egg. After menopause, the ovaries stop releasing eggs and cease production of the hormone estrogen. However, they will still continue to produce testosterone alongside the adrenal glands.
The ovaries become slightly smaller after menopause, but won't disappear. Normally, only one egg is released during ovulation, but it is possible for both ovaries to release an egg at the same time. In about half of hysterectomies, the ovaries are removed as well, in a procedure known as an oophorectomy. In some cases, they may result from hormonal treatments, including fertility treatments. Other causes include polycystic ovary syndrome PCOS , endometriosis a condition in which uterine tissue may be found outside the uterus , or a pelvic infection.
Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Cleveland Clinic. Last reviewed November 24, A review of ovary torsion. Mosby; American College of Obstetricians and Gynecologists. Ovarian cysts. 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. 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, the 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 syndrome , can 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. The second phase of development requires gonadal hormone stimulation to stimulate further development. However, even though hundreds of eggs have begun to mature, most often only one egg will become dominant during each menstrual cycle, and reach its' fully mature state, capable of ovulation and fertilization.
Pre-pubertal girls do not produce the gonadal hormones that are necessary for the second phase of development, so the many eggs that started to mature will simply wither away. The large number of eggs that are used each month account for the steady decline in the female's total egg pool that occurs from birth to menopause.
In post-pubertal females, the dominant egg continues to develop, relying on hormones for growth and stimulation.
When the egg becomes fully mature, the follicle surrounding the egg bursts, and releases a mature egg which travels through the fallopian tube toward the uterus. The egg is capable of being fertilized for a short period, about 48 hours. If the egg is not fertilized during this time, it will die, and in another week or so, a new cycle of egg maturation will begin.
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