Learn how humans develop from a human seed[sperm]

From Embryo to Fetus in the womb : medical facts
by Gloria Poole,R.N.
There are several distinguishing features of the
transition of an embryo to a fetus. Both of these words
are medical terms for a certain stage of development in
the womb. There is no abrupt change from the embryo to
the fetus. Instead there are cumulative changes that are
evolving day to day. The embryo changes from an
amorphous shape to more of a tiny human with all parts.
Also all of the major body organs have either appeared
or the precursor of them has developed. As the embryo
survives the second month in the womb, and is alive at
the beginning of the third month, the tiny human is less
vulnerable to the effects of disease in the mother, or
radiation of the mother, or medicines the mother may
have taken. Of course women who are pregnant should
never drink alcohol or use drugs, or smoke! At any stage of the
pregnancy the baby in the womb is harmed by alcohol, and
many drugs have teratogenic effects.
The term fetus is appropriate after the major organs are either formed
entirely or the precursor of them is present e.g. for
the kidney. The fetus is still vulnerable but not as
much so, since the tiny human has a larger body and
therefore it would take larger doses of medicines
through the placenta to harm the tiny being, and the
tiny baby also has more developed organs to filter the
medicines that might pass to the baby through the
placenta.
At the end of the first month after
fertilization the human embryo is about a quarter of an
inch in length from the top of the flat bulbous like
head to the end of the emerging legs that look at first
like a tail. Most of the organs are beginning to take
shape as the cells continuously divide and
differentiate. The tiny human develops by a 'blue print'
that is built into the chromosones and genes that the
tiny human received from the mother and from the father.
Twenty-three chromosones come from each parent in most
instances. In Down's syndrome the chromosones are
different. The baby's brain develops first since it is
needed first. The wisdom of GOD in creating humans is
obvious if you really study human anatomy and physiology
much. The outlines of eyes appear and a primitive mouth
and by 30 days after fertilization the three primary
parts of the brain are present , and the eyes, ears, and
nasal passages have begun to develop. The beginnings of
the backbone is present but that first month the tiny
embryo is sort of hunched together in a C shape. There
is no discernible arms or legs yet but the "tail" will
become legs. The heart will have started beating even
though it is not completely formed. The tiny human has
a closed circulatory system that includes the baby's own
blood vessels and also the umbilical cord and placenta
to the mother. The digestive tract opens from the mouth
downward for the first time on about the 28 th day
after fertilization by the male sperm. The liver appears
by about the 21 st day after fertilization. The thyroid
gland begins to form. The stomach, intestines,liver and
pancreas are there but there is no anus yet. The lungs
are not developed yet. Lung buds begin about day 27 and
the trachea [windpipe ] appears a few days after that.
By the time the tiny being would be called a fetus he or
she would have gained weight to one gram or about one-
thirtieth of an ounce, which is not as much as an
aspirin tablet but for the tiny human it is significant
progress since it means a 50-fold gain in body mass
gained during the second month over again what the tiny
human weighed at the end of four weeks after
fertilization. By day 31 muscles appear in the pelvis
and arms and legs begin to form and look sort of like a
bud on a tree in bloom.The valve separating the chambers
of the heart appear on day 31 or soon after. The germ
cells [sex determining] move along the mesoderm toward
the genital ridges and will form either ovaries or
testicles. By day 32 the caudal muscles appear [in what
becomes the baby's behind] and the last pair of gill-
like arches that will develop into lungs appears. By day
33 the cerebral cortex in the brain develops. By day 34
more of the muscles that will become the thighs and legs
develop and the stalk that separates the baby from the
yolk sac lengthens. By day 35 the primitive germ cells
have arrived in large numbers near the ridge that
develops into the kidney. And the olfactory part of the
brain that regulates smell is present in the brain. By
the fifth week the tiny human is 8 millimeters or one-
third of an inch long from crown to rump and weighs
about 1/1000 of an ounce. The jaws are forming and the
face is beginning to look like a human face. The
umbilical cord is present and is the only part connected
to the placenta. The pituitary gland is forming in the
middle of the brain. The pharynx branches into the two
parts that will go to each lung. The membranes
[peritoneum] that separate the intestines form the chest
have formed and separate the lungs,heart and trachea
from the stomach and intestine. By day 36 the arm and
legs buds appear, and the 'tail' starts to shrink and
the baby may start moving about.

By day 37 the intestines have grown enough that they are
beginning to curve into their adult shape. The brain
stem that controls respiration is recognizable. By day
38 the jaws of upper and lower begin to look symmetrical
and with an mouth between them and the eye muscles have
begun to form in the orbits. Hands that look more like
paddles form and then when the fingers elongate they
look more like hands. The insides of the baby have grown
so fast that they sort of bulge and could be seen easily
through the almost transparent skin of the baby. By day
39 the nerve fibers are present to connect the sense of
smell of the olfactory nerves. By day 40 the pigment
[color] of the eyes could be seen through the
transparent skin also. The jaws are well formed and the
teeth, and facial muscles are forming also. The gill
arches disappear and the diaphragm appears that moves up
and down in respirations though the baby does not
breathe in the womb but later sort of practices that
effort. The liver starts producing red blood cells and
takes over from the yolk sac. By day 42 the reflexes
being and fingers and toes are more visible and the
beginnings of gonads are visible. By the sixth week the
fetus is 13 millimeters or half an inch long from crown
to rump. Cartilage that will become bone appears. The
head seems huge in relation to the rest of the body and
bends forward onto the chest since baby is still sort of
a C shape. Fingers appear. And the mammary glands begin.
The stomach and intestines rotate into position, muscles
lengthen and both cartilage and bone are visible in the
forming skeleton. The kidney has begun with the
pronephros the first but non-functioning kidneys. By day
44 the retinas of the eyes form, and also the palate of
the mouth and and the canals of the ear. By day 46 the
gonads are formed either ovaries or testicles so the sex
of the baby. Viola! By day 48 after fertilization the
tiny human looks like a human! And is definitely a
fetus.

/s/ Gloria Poole, R.N. with reference from medical

textbook "From Conception to Birth' by Roberts Rugh and Landrum B Shettles MDs.

The medical facts of how humans develop is written by me on another website of mine that is unique [different from any other] at: http://onlineeducator.bravehost.com.

And the sketches I drew of some of the stages of human development and wanted to add to this website but they vanished from uploader AGAIN; so I added them to this website of mine: http://onlineeducator.biz/ and look at the entry of yesterday 6-June-2009. They are a series of about 7 or 8 sketches in pencil and watercolor showing stages of development of human beings in the womb.

This document is owned by, and written by Gloria Poole,RN; and this blog and this computer are also owned privately by me [Gloria Poole,RN of Missouri].And added to this blog on 26-Feb-2011 as teaching how humans develop in womb. .