Conception to Birth
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About
three hundred million sperms are ejaculated and
deposited in the vagina during an act of intercourse.
The fertile cervical mucus helps the sperms survive
the journey to meet the egg in the Fallopian tube.
It filters out abnormal sperms and enables the healthy
ones to enter the cervix through channels or passageways,
as if swimming up a river. |
| The mucus
also nourishes the sperms so they will be full of
energy and vitality when they reach the egg in the
tube. In addition, the mucus keeps some sperms alive
and healthy for three to five days in the cervical
crypts (tiny "niches" in the cervical
wall). |
The surviving sperms must travel the length of the
uterus as they make their way toward the tubes. The
sperm cannot know whether the egg is to the right or
to the left, so they enter both tubes. Of the millions
of sperms that enter the vagina, only a few hundred
will actually reach the fallopian tubes and only one
will penetrate and fertilize the egg. Once, fertilization
takes place, the outer wall of the ovum hardens preventing
the other sperms from entering it. These other sperms
ultimately die out.
FERTILIZATION TO IMPLANTATION
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| 30 Hrs |
45 Hrs |
72 Hrs
Morula |
4-6 Days
Blastocyst
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7-13 Days
Implanted Embryo |
Conception occurs as the sperm and egg unite to form
a single cell, and new human life begins. This is the
first stage of human life. All of us began our lives
from this stage of being a single cell. The scientific
term for this is fertilization. After fertilization
occurs, the zygote divides, in 30 hours time, into two
cells, these two, after two days become 4 cells, then
into 8 cells and so on. By about the third day the zygote
is a solid mass of closely packed cells, about hundred
in number, called the "morula" (Latin word
for mulberry). Fluid enters the zygote due to which
a cavity is formed splitting the morula cells into two
parts, an outer layer of cells and a clump of cells
at one side. This structure is called a blastocyst.
The outer cells will become the placenta, while the
inner cell mass will form the embryo.
By the fourth day it enters the uterus. By the seventh
or eighth day the outer wall of the blastocyst breaks
down and it gets attached to the spongy nourishing lining
of the womb that was prepared for it by the action of
oestrogen and progesterone. The process of attachment
is called nidation or implantation. By the ninth day
after fertilization the blastocyst has burrowed deep
into the lining and is the size of a pin-head. Four
days later (at the time of the expected menstruation)
it has grown enough to be just visible to the naked
eye. The cervical canal is filled with a plug of thick
mucus that prevents any harmful substance, bacteria,
etc from entering into the uterine cavity and disturbing
the growth of the delicate human life that has just
begun.
STAGES OF FETAL DEVELOPMENT
Fertilization:
When the sperm meets the ovum it is a single cell about
0.1mm in size and has its own DNA material, which determines
its sex and colour of the hair, eyes, etc. It remains
a single cell for the first twelve hours.
30 hours: |
2 cell stage |
| 45 hours : |
4 cell stage |
| 3 days: |
16 cell stage called Morula (Latin word for mulberry). |
| 4-6 days |
Blastocyst, consists of hundreds of cells and
is the size of a pinhead. |
| 6th day: |
Implantation begins and is completed within the
next 7 days i.e. around the next period. Mild spotting
may occur. |
| 14 days: |
Called an embryo until the end of eight weeks.
|
| 22 days: |
Heart (as two tubes) starts to beat for the first
time. |
| 25 days: |
The baby's body is beginning to develop. Head,
trunk and arm buds begin to appear. Other internal
organs are present in simple form and function as
they grow. |
| 30 days: |
Just two weeks after the mother's first missed
period, the baby is a quarter inch long, has a brain
of unmistakable human proportions, has eyes, ears,
mouth, kidneys, liver, an umbilical cord and a heart
pumping blood. "He has made himself",
as described by a doctor who performed the first
ever blood transfusion on an unborn baby. Head and
back grows rapidly because of rapidly growing Central
Nervous System (CNS). |
| 6 weeks: |
Tiny fingers appear, followed within days, by
toes. Eyes develop lens and retina followed by eyelids.
Brain waves can be detected. |
7 weeks:
|
The baby has developed individual fingerprints.
The outer ear is present. The inner ear with its
hearing and balancing mechanism is well established.
Sensory nerves develop which are more sensitive
to that of an adult or a new born. Skeleton is complete
in cartilage form. Movements are seen but are not
strong enough to be perceived by the mother. |
| 8 weeks: |
Crown rump length is 40mm and is termed as embryo
until the end of eight weeks. (Gk. embruon means
to grow). The skeleton begins to turn from cartilage
to bone. |
| 9 weeks: |
Called fetus (Latin word for offspring). Bends
fingers around an object in the palm of his hand.
In response to touch on the sole of his foot, he
will curl his toes or bend his hips and knees to
move away from the touching object. |
| 10 weeks: |
Brain cells which are essential for consciousness
in the adult, are known to be present in the fetus
by 10 weeks. Nerve fibres which transmit pain impulses
are known to be present even before fibres inhibiting
pain have developed, which implies that the first
trimester fetus may be more susceptible to pain
than at any later stage. Brain waves can be recorded
i.e. EEG (Electroencephalogram). |
| 11 weeks: |
The baby swallows its own amniotic fluid. Breathing
movements are seen. Facial expressions are observed. |
| 12 weeks: |
The features are becoming more defined. The unborn
baby wrinkles her forehead, raises her eyebrows
and turns her head. She measures 90mm and weighs
around 45grams. |
| 16 weeks: |
The baby is 1/3rd the size at full term. She measures
140mm in length and weighs 200 grams. She can hear
and is sensitive to light. When light is shone on
the mother's abdomen, the heartbeat of the baby
changes. Similar response to sound is observed.
Waking and sleeping patterns are seen. |
| 20 weeks: |
Measures 190mm and weighs 460grams. Hair, eyebrows,
eyelashes and nails grow. The baby is covered with
vernix caseosa, a greasy substance, which protects
her from prolonged contact with the amniotic fluid.
The baby will gain weight and develop an insulating
layer of fat beneath the skin. The baby will receive
maternal antibodies against some infections as a
temporary protection until the infant's own immune
system is better developed. |
| 30 weeks: |
For several months, the umbilical cord has been
the baby's lifeline to the mother. Nourishment is
transferred from the mother's blood, through the
placenta, and into the umbilical cord to the fetus.
If the mother ingests any toxic substances, such
as drugs or alcohol, the baby receives these as
well. |
| 32 weeks: |
The fetus sleeps 90-95% of the day, and sometimes
experiences REM sleep, an indication of dreaming.
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| 40 weeks: |
The baby is ready for life outside its mother's
womb. At birth the placenta will detach from the
side of the uterus and the umbilical cord will cease
working as the child takes his first breath of air.
The child's breathing will trigger changes in the
structure of the heart and bypass arteries, which
will force all blood to now travel through the lungs. |
Human development is a continuous process that begins
at fertilization. The human life continues to grow within
the womb for a period of approximately 9 months. When
the child is about to be delivered, the bag of waters
(amniotic fluid) breaks and the uterus begins to contract,
thus resulting in minor labor pains. At this time the
mother is rushed to the hospital and within a duration
of 12-24 hours, the child is delivered.
DELIVERY
All through the nine months, the breasts of the women
are also prepared to nurture the new born, so that at
birth, when the baby is delivered, the breasts begins
to function as soon as the baby feeds through its sucking
action.
Many women think that menstruation is the sure sign
of the return of fertility. This presumption is an error.
The fertility sign is the egg white type, thin, slimy,
fertile mucus. Thus, when the pituitary gland sends
signals to the ovaries through the Follicle Simulating
Hormone (FSH), the follicles begin to mature. As explained
earlier, the mature follicle gives out an ovum, accompanied
by the release of fertile mucus, as an outward sign.
And, the menstruation follows normally, if that egg
(ovum) is not fertilized.
Hereditary Characteristics:
The hereditary characteristics of the parents that
are contained in the sperm and egg mingle and are passed
on to their child. At this moment, the new person's
genetic makeup viz. the colour of his eyes, hair and
so forth is determined. He is unique and unrepeatable.
We know that all the genetic information is there to
tell us that there is a link between the parents and
the children. As soon as the 23 chromosomes carried
by the sperm encounter the 23 chromosomes carried by
the ovum, the whole information necessary and sufficient
to spell out all the characteristics of the new being
is gathered.
Now, chromosomes are a long thread of DNA (DNA is the
coded information for every living thing's heredity,
responsible for the passing of characteristics from
parents to offspring). Chromosomes consist of many DNA
units called genes in which information is written.
They are coiled very tightly in the chromosomes, and,
in fact, a chromosome can be compared to a mini-cassette,
in which a symphony is written, 'the symphony of life.' |
