Female Reproductive System

Picture of Female Infertility

The female reproductive system is made up of internal organs and external structures. Its function is to enable the reproduction of the species. Sexual maturation is the process that this system undergoes in order to carry out its role in the process of pregnancy and birth.

Picture of the internal female reproductive system

Internal reproductive organs

• Uterus (womb)
• Cervix
• Fallopian tubes
• Ovaries
• Vagina

The uterus, or womb, is a hollow organ located centrally in the pelvis. It houses the developing fetus during pregnancy.

The lower portion of the uterus is called the cervix and opens into the vagina or birth canal. An opening in the cervix allows for the passage of sperm into the uterus and the exit of menstrual blood. This same opening dilates during labor to allow passage of the baby through the birth canal.

Arising from the upper portion of the uterus on each side are the Fallopian tubes. These are channels that allow eggs from the ovaries to enter the uterus. The process of fertilization of an egg by a sperm cell typically happens in the Fallopian tubes, and the fertilized egg moves into the uterus where it is implanted.

Beside the uterus on each side and near the opening of the Fallopian tubes are the small, oval ovaries. They produce hormones and contain eggs.

At birth, a female has 1 to 2 million eggs already present in the ovaries, but only about 300 of them will mature during a woman's lifetime.

• The labia majora are two fleshy protrusions that protect and envelop the other external reproductive organs. They are covered with hair after puberty. 
• They contain glands that produce sweat and oils. Inside the labia, majora are the labia minora, smaller protrusions of flesh that surround the openings to the urethra (that allows passage of urine) and the vagina.
• Located next to the vaginal opening are glands that produce mucus known as Bartholin's glands. At the junction of the labia minora is the clitoris, a small structure that is covered by a skin fold called the prepuce.
• The clitoris is comparable to the male penis and is highly sensitive.

The menstrual cycle is the monthly cycle of follicle and egg maturation, the release of an egg (ovulation), and the preparation of the uterine lining for pregnancy. If a woman does not become pregnant, the uterine lining tissue is shed as menstrual blood.

Most menstrual cycles occur every 28 days. Menarche is the time during adolescence when menstrual periods begin. Menstrual periods continue to occur until a woman reaches menopause.

The follicular phase is the beginning of the menstrual cycle. It starts on the first day of menstrual bleeding and usually lasts about 14 days.

• The hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are released from the pituitary gland to stimulate the ovaries.
• In turn, the ovaries produce estrogen and stimulate the maturation of about 15 to 20 eggs in the ovaries inside small cystic areas known as follicles.
• Once estrogen levels begin to rise, the secretion of FSH is reduced by a feedback system so that follicle stimulation ceases at the appropriate time.
• With time, one of the egg follicles (or rarely, two or more) becomes dominant, and maturation of the other follicles is interrupted. The dominant follicle continues to make estrogen.

Ovulation occurs at the midpoint of the menstrual cycle.

• Estrogen production from the dominant follicle leads to a sharp rise in LH secretion, causing the dominant follicle to release its egg.
• The egg is swept into the Fallopian tube by thin structures on the ends of the tubes known as fimbriae.
• At this time, the cervix produces an increased amount of thin mucus that assists sperm in the passage into the uterus.

The luteal phase of the menstrual cycle begins at ovulation (egg release).

• After the egg is released, the empty follicle turns into a cystic mass of cells called the corpus luteum.
• The corpus luteum then produces progesterone, a hormone that readies the lining of the uterus for the implantation of a fertilized egg.
• If an egg has been fertilized, the fertilized egg travels down one of the Fallopian tubes into the uterus and implants in the uterine lining tissue.
• If fertilization of an egg has not occurred, the lining of the uterus eventually breaks down and is shed resulting in menstrual bleeding.

Menopause is defined as the point in time at which a woman has not had a menstrual period for 12 consecutive months.

• It signals the end of a woman's fertility and occurs, on average, at 51 years of age, though the time of menopause can vary widely.
• With menopause, hormone levels drop, and some women experience unpleasant effects from the lowered hormone levels, including hot flashes, mood changes, headaches, tiredness, and sleep disturbances.