Female Internal Genital Organs

The vagina is a soft, stretchable tube of muscle tissue about 4 to 5 inches long in an adult woman. It connects the external genital organs Female External Genital Organs The external genital structures include the mons pubis, labia majora, labia minora, and clitoris. The area containing these structures is called the vulva. The external genital structures have... read more to the uterus. The upper part of the vagina is wider and surrounds the cervix (the lower part of the uterus). Some types of birth control (such as a diaphragm or vaginal ring) or drugs are inserted here.

The vagina has a central role in sexual activity and reproduction. It is the passageway for the following:

Because the vaginal tissue is soft, its walls can stretch open for examination by a doctor, for sexual intercourse, or for childbirth. After menopause Effects of Aging on the Female Reproductive System Around menopause, changes in the female reproductive organs occur rapidly. (Menopause is defined as 1 full year after the last menstrual period.) Menstrual cycles stop, and the ovaries stop... read more , the vagina becomes less stretchy because estrogen levels decrease. This change can cause pain.

The vagina is lined with a mucous membrane, kept moist by fluids produced by cells on its surface and by secretions from glands in the cervix. A small amount of these fluids may pass to the outside as a clear or milky white vaginal discharge, which is normal. During a woman's reproductive years, the lining of the vagina has folds and wrinkles. Before puberty and after menopause, the lining is smooth.

The uterus is a thick-walled, muscular, pear-shaped organ located in the middle of the pelvis, behind the bladder, and in front of the rectum. The uterus is anchored in position by several ligaments. The main function of the uterus is to sustain a developing fetus.

The uterus consists of the following:

The cervix is the lower part of the uterus, which protrudes into the upper part of the vagina. During a pelvic examination Pelvic Examination For gynecologic care, a woman should choose a health care practitioner with whom she can comfortably discuss sensitive topics, such as sex, birth control, pregnancy, and problems related to... read more , doctors can examine the cervix using a speculum (a metal or plastic instrument that spreads the walls of the vagina apart). Like the vagina, the cervix is lined with a mucous membrane.

Sperm can enter and menstrual blood can exit the uterus through a channel in the cervix (cervical canal). The cervical canal is usually narrow, but during labor, the canal widens to let the baby through.

The cervix is usually a good barrier against bacteria. However, the bacteria that cause sexually transmitted diseases Overview of Sexually Transmitted Infections (STIs) Sexually transmitted infection (STI) refers to an infection that is passed through blood, semen, vaginal fluids, or other body fluids during oral, anal, or genital sex with an infected partner... read more can enter the uterus through the cervix during sexual intercourse.

The channel through the cervix is lined with cells and glands that secrete mucus. This mucus is thick and impenetrable to sperm until just before ovulation. At ovulation, the mucus becomes clear and elastic (because the level of the hormone estrogen increases). As a result, sperm can swim through the mucus into the uterus to the fallopian tubes, where fertilization can take place.

Almost all pregnancies result from intercourse that occurs during the 3 days before ovulation. However, pregnancies sometimes result from intercourse that occurs up to 6 days before ovulation or during the 3 days after ovulation. For some women, the time between a menstrual period and ovulation varies from month to month. Consequently, pregnancy can occur at different times during a menstrual cycle Menstrual Cycle Menstruation is the shedding of the lining of the uterus (endometrium) accompanied by bleeding. It occurs in approximately monthly cycles throughout a woman's reproductive life, except during... read more .

The corpus of the uterus, which consists of muscle tissue, can stretch to accommodate a growing fetus. Its muscular walls contract during labor to push the baby out through the cervix and the vagina. During the reproductive years, the corpus is twice as long as the cervix. After menopause, th uterus and cervix are about the same length.

As part of a woman's reproductive cycle (which usually lasts about a month), the lining of the corpus (endometrium) thickens. If the woman does not become pregnant during that cycle, most of the endometrium is shed and bleeding occurs, resulting in the menstrual period.

The two fallopian tubes, which are about 4 to 5 inches (about 10 to 13 centimeters) long, extend from the upper edges of the uterus toward the ovaries. The tubes do not directly connect with the ovaries. Instead, the end of each tube flares into a funnel shape with fingerlike extensions (fimbriae). When an egg is released from an ovary, the fimbriae guide the egg into the opening of a fallopian tube.

The fallopian tubes are lined with tiny hairlike projections (cilia). The cilia and the muscles in the tube's wall propel an egg downward through the tube to the uterus. The fallopian tube is the usual site of fertilization Fertilization A baby goes through several stages of development, beginning as a fertilized egg. The egg develops into a blastocyst, an embryo, then a fetus. During each normal menstrual cycle, one egg (ovum)... read more of the egg by the sperm. After fertilization, the fertilized egg enters the uterus and implants there.

The ovaries are usually pearl-colored, oblong, and about the size of a walnut. They are attached to the uterus by ligaments. In addition to producing female sex hormones (estrogen and progesterone) and some male sex hormones, the ovaries produce and release eggs. The developing egg cells (oocytes) are contained in fluid-filled cavities (follicles) in the wall of the ovaries. Each follicle contains one oocyte.