The Female Reproductive System
The female reproductive system is designed to carry out
several functions. It produces the female egg cells necessary for reproduction,
called the ova or oocytes. The system is designed to transport the ova to the
site of fertilization. Conception, the fertilization of an egg by a sperm,
normally occurs in the fallopian tubes. After conception, the uterus offers a
safe and favorable environment for a baby to develop before it is time for it to
make its way into the outside world. If fertilization does not take place, the
system is designed to menstruate (the monthly shedding of the uterine lining).
In addition, the female reproductive system produces female sex hormones that
maintain the reproductive cycle.
During menopause the female reproductive system gradually
stops making the female hormones necessary for the reproductive cycle to work.
When the body no longer produces these hormones a woman is considered to be
What parts make-up the female anatomy?
The female reproductive anatomy includes internal and
The function of the external female reproductive structures
(the genital) is twofold: To enable sperm to enter the body and to protect the
internal genital organs from infectious organisms. The main external structures
of the female reproductive system include:
- Labia majora: The labia majora enclose and protect
the other external reproductive organs. Literally translated as "large
lips," the labia majora are relatively large and fleshy, and are
comparable to the scrotum in males. The labia majora contain sweat and
oil-secreting glands. After puberty, the labia majora are covered with hair.
- Labia minora: Literally translated as "small
lips," the labia minora can be very small or up to 2 inches wide. They
lie just inside the labia majora, and surround the openings to the vagina (the
canal that joins the lower part of the uterus to the outside of the body) and
urethra (the tube that carries urine from the bladder to the outside of the
- Bartholinís glands: These glands are located next
to the vaginal opening and produce a fluid (mucus) secretion.
- Clitoris: The two labia minora meet at the clitoris,
a small, sensitive protrusion that is comparable to the penis in males. The
clitoris is covered by a fold of skin, called the prepuce, which is similar to
the foreskin at the end of the penis. Like the penis, the clitoris is very
sensitive to stimulation and can become erect.
The internal reproductive organs include:
- Vagina: The vagina is a canal that joins the cervix
(the lower part of uterus) to the outside of the body. It also is known as the
- Uterus (womb): The uterus is a hollow, pear-shaped
organ that is the home to a developing fetus. The uterus is divided into two
parts: the cervix, which is the lower part that opens into the vagina, and the
main body of the uterus, called the corpus. The corpus can easily expand to
hold a developing baby. A channel through the cervix allows sperm to enter and
menstrual blood to exit.
- Ovaries: The ovaries are small, oval-shaped glands
that are located on either side of the uterus. The ovaries produce eggs and
- Fallopian tubes: These are narrow tubes that are
attached to the upper part of the uterus and serve as tunnels for the ova (egg
cells) to travel from the ovaries to the uterus. Conception, the fertilization
of an egg by a sperm, normally occurs in the fallopian tubes. The fertilized
egg then moves to the uterus, where it implants to the uterine wall.
What happens during the menstrual cycle?
Females of reproductive age (anywhere from 11-16
years) experience cycles of hormonal activity that repeat at about one-month
intervals. (Menstru means "monthly"; hence the term menstrual
cycle.) With every cycle, a womanís body prepares for a potential pregnancy,
whether or not that is the womanís intention. The term menstruation
refers to the periodic shedding of the uterine lining.
The average menstrual cycle takes about 28 days and occurs in
phases: the follicular phase, the ovulatory phase (ovulation), and the luteal
There are four major hormones (chemicals that stimulate or
regulate the activity of cells or organs) involved in the menstrual cycle:
follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone.
This phase starts on the first day of your period.
During the follicular phase of the menstrual cycle, the following events occur:
- Two hormones, follicle stimulating hormone (FSH) and
luteinizing hormone (LH) are released from the brain and travel in the
blood to the ovaries.
- The hormones stimulate the growth of about 15-20 eggs in
the ovaries each in its own "shell," called a follicle.
- These hormones (FSH and LH) also trigger an increase in
the production of the female hormone estrogen.
- As estrogen levels rise, like a switch, it turns off the
production of follicle-stimulating hormone. This careful balance of
hormones allows the body to limit the number of follicles that complete
maturation, or growth.
- As the follicular phase progresses, one follicle in one
ovary becomes dominant and continues to mature. This dominant follicle
suppresses all of the other follicles in the group. As a result, they stop
growing and die. The dominant follicle continues to produce estrogen.
The ovulatory phase, or ovulation, starts about 14
days after the follicular phase started. The ovulatory phase is the midpoint of
the menstrual cycle, with the next menstrual period starting about 2 weeks
later. During this phase, the following events occur:
- The rise in estrogen from the dominant follicle triggers
a surge in the amount of luteinizing hormone that is produced by the
- This causes the dominant follicle to release its egg from
- As the egg is released (a process called ovulation) it is
captured by finger-like projections on the end of the fallopian tubes (fimbriae).
The fimbriae sweep the egg into the tube.
- Also during this phase, there is an increase in the
amount and thickness of mucus produced by the cervix (lower part of the
uterus.) If a woman were to have intercourse during this time, the thick
mucus captures the man's sperm, nourishes it, and helps it to move towards
the egg for fertilization.
The luteal phase begins right after ovulation and
involves the following processes:
- Once it releases its egg, the empty follicle develops
into a new structure called the corpus luteum.
- The corpus luteum secretes the hormones estrogen and
progesterone. Progesterone prepares the uterus for a fertilized egg to
- If intercourse has taken place and a man's sperm has
fertilized the egg (a process called conception), the fertilized egg
(embryo) will travel through the fallopian tube to implant in the uterus.
The woman is now considered pregnant.
- If the egg is not fertilized, it passes through the
uterus. Not needed to support a pregnancy, the lining of the uterus breaks
down and sheds, and the next menstrual period begins.
How many eggs does a woman have?
During fetal life, there are about 6 million to 7
million eggs. From this time, no new eggs are produced.
The vast majority of the eggs within the ovaries steadily die,
until they are depleted at menopause. At birth, there are approximately 1
million eggs; and by the time of puberty, only about 300,000 remain. Of these,
300 to 400 will be ovulated during a woman's reproductive lifetime. The eggs
continue to degenerate during pregnancy, with the use of birth control pills,
and in the presence or absence of regular menstrual cycles.
Copyright 1995-2005 The Cleveland Clinic Foundation. All rights reserved