from
the book How to Have a Baby: Overcoming Infertility
by Dr. Aniruddha Malpani, MD and Dr. Anjali Malpani,
MD.
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Do you have an infertility problem?
When to start worrying!
Next page: How
Babies are Made - The Basics (Page 2)
Table of Contents
How
does a woman's reproductive system function ?
Every school child knows that you need
eggs and sperm to make a baby. However, we need to examine
the basics in greater detail , so let’s start by taking
a guided tour of the reproductive system.
How does a woman's
reproductive system function ?
The sexual and reproductive organs on the outside of
the body are called the external genitals. There are
three openings in the genital area. In front is the
urethra, from where urine comes out; below this is the
opening to the vagina which is called the introitus
; and the third is the anus from where a bowel movement
leaves the body.
The outer genital area is called the
vulva. The vulva includes the clitoris, the labia majora
and the labia minora. The most sensitive part of the
genital area is the clitoris. This is a pea shaped organ
that's full of nerve endings since its only purpose
is to provide sexual pleasure. The clitoris is protected
by a hood of skin, and is the equivalent of the man's
penis.
The labia majora, or outer lips, surround
the opening to the vagina. They are made of fatty tissue
that cushions and protects the vaginal opening. Between
these outer lips are labia minora, or inner lips. These
are sensitive to sexual pleasure. As they are stimulated,
they get deeper in color and swell.
The vagina is a muscular tunnel that
connects the uterus to the outside of the body. It provides
an exit for the menstrual fluid; and an entrance for
the semen. Normally flat, like a collapsed balloon,
the vagina can stretch to accommodate a tampon, a penis
or a baby's head. The walls of the vagina are muscular,
smooth and soft. The vagina is a closed space which
ends at your cervix.
The uterus, or the womb, is the place
where the fertilized egg grows and develops into a baby
during pregnancy. The uterus lies deep in the lower
abdomen - the pelvis - and is just behind the urinary
bladder. It is a hollow organ shaped like a pear and
is about the size of the fist. Inside the muscular walls
of the uterus is a very rich lining - the endometrium,
and it is in this lining that the fertilized egg implants.
If pregnancy does not occur, the lining is shed along
with blood as the menstrual flow.
The neck of the uterus is called the
cervix. It connects the uterus to the vagina and contains
special glands called crypts that make mucus which helps
to keep bacteria out of the uterus. The cervical mucus
also helps sperms to enter the uterus when the egg is
ripe.
The two fallopian tubes ( also known
as oviducts) are attached to the upper part of the uterus
on either side and are about 10 cm long. They are about
as big as a piece of spaghetti . Each tube forms a narrow
passageway that opens like a funnel into the abdominal
cavity, near the ovaries. The ends of the fallopian
tubes are draped over the two ovaries and they serve
as a passageway for the egg to travel from the ovary
into the uterus. The tube is lined by millions of tiny
hairs called cilia, that beat rhythmically to propel
the egg forward. Of course, the tube is not just a pathway
- it performs other functions too, including nourishing
the egg and the early embryo in its cavity. Also, the
sperm fertilizes the egg in one of the fallopian tubes.
The two almond-sized ovaries are perched
in the pelvis, one on each side, just within the fallopian
tubes' grasp. The ovary serves two functions: the production
of eggs and the secretion of hormones. Each month, at
the time of ovulation, a mature egg is released by an
ovary. This is "picked up " by the fimbria and drawn
into the fallopian tubes.
The eggs in the ovary are stored in
follicles (from folliculus, meaning sack in Latin).
These cellular sacks contain the eggs; as well as granulosa
cells and theca cells which nurture the egg , and produce
the female hormones. The ovary has about 2 million eggs
during fetal life. From that point onwards, the number
of eggs progressively decreases, till only about 300,000
eggs are left at the time of birth - a lifetime's stock.
During the fertile years fewer than 500 of these eggs
will be released into the fallopian tubes - once in
each menstrual cycle. Unlike the testis which is continually
churning out billions of new sperm, the ovary never
produces any new eggs. One of the existing eggs is matured
for ovulation each month - and this limited supply runs
out at the time of menopause.
Figure 1. Female external genitalia
Figure 2. The female reproductive system
The aspect of the reproductive system that women are
most aware of is the menstrual period which they have
every month. The menstrual cycle is the time from the
beginning of one period to the beginning of the next
one. Usually menstrual cycles last about 28- 35 days,
though anywhere from 3 to 6 weeks is considered normal
.
During the menstrual cycle, the uterus
gets ready for pregnancy. Under the influence of the
hormones estrogen and progesterone, its lining grows
rich and thick to prepare for the fertilized egg. If
pregnancy doesn't occur, the uterus must get rid of
this lining so that it can grow a new one in the next
cycle. The old lining passes out of the uterus through
the vagina as the menstrual flow.
The menstrual flow thus consists of:
- the shed uterine lining
- blood (this comes from the blood
vessels which are torn when the lining is shed)
- the degenerated unfertilised egg
If the menstrual flow is heavy, there
may sometimes be clots in it. Sometimes the uterine
lining is shed as large fragments - and these may sometimes
looks like bits of pregnancy tissue to some women, who
think they are miscarrying.
Many infertile women are obsessed
with their menstrual periods, and they worry about every
little variation – whether it’s too dark, too light,
too much or too little. However, remember that the menstrual
flow has no connection to your fertility and you should
not be too concerned about variations, which are quite
common and of little significance.
continued . .
.
Next page: How
Babies are Made - The Basics (Page 2)
Previous page:
Do
you have an infertility problem? When to start worrying!
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