did you know you were once a stem-cell? believe it or not, on the day one the
embryo created you looked like a cell in this picture and you became an
eight-cell embryo on day three. What was your first stem-cell? How human
formed from just a single stem cell to a baby? molecular doctor will uncover the
mysteries of biological world, stay tuned!
A human body comprises more than 200 types of cells the largest cell in the
human body is the female egg also known as ovum, while the smallest cell is the
sperm. The ovaries produce the female egg cells, normally each woman has two
ovaries.
the ovaries a pair of tiny glands in the
female pelvic cavity are the female reproductive organs that house the
eggs, and are responsible for the production of sex hormones, progesterone
and estrogen. A human egg cell is immobile, the eggs love to stay at their
sweet home. The ovaries produce and release eggs.
typically only one ripe egg is released per menstrual cycle
Every 28 days or so one mature egg is released from the ovary, this is called
ovulation. Following ovulation the finger-like end of the Fallopian tube
are responsible for egg pick up and movement into the tube where the egg can
live for about 24 hours. Testis, an organ that produces sperm and
releases important sexual hormone of males, androgen particularly testosterone.
A pair of glands that produce the male reproductive cells, so the testes are
known as 'Sperm Factory'. the ultimate goal of sperm is to
fertilize the egg. To succeed in their mission sperm has to be good at two
things: swimming and drilling. Normal sperm motility plays a big role in men's
reproductive health.An egg lives about 24 hours after leaving the ovary, sperm
can fertilize the ready egg in the fallopian tube during a 6 to 12 hour
period that is the magic moment that sperm meeting with the egg. The average
of ejaculate contains 200 million sperm, it takes only one sperm to
fertilize an egg, therefore this is the toughest competition in the world.
200 million sperms start a dangerous journey. How fast do sperm swim? The
answer is about 5 millimeters per minute. How do they find the egg? Sperm
recognizes egg by two means, one is a thermal gradient; the second is that
egg oozes out various attractive molecules.
Fertilization occurs when the nucleus of both a sperm and an egg fused to form a diploid cell known as
a zygote, the first stem cell in human body.
All cells in human body are diploid except the germ cells, eggs and sperm. They have only
half the number of chromosomes(23 chromosomes). When egg and sperm fuse into
one, a new cell with 46 chromosomes containing both parents genetic material.
in the nucleus of each human cell the DNA molecule is packaged into
thread-like structures called chromosomes. The DNA molecule contains
part or all of the genetic material, genome of a person. A human cell contains
22 pairs of autosomes and one pair of sex chromosomes.
Females have two copies of the X chromosome, while males have One X and
one Y chromosome. Who determines the gender of the child? sperm or egg?
Scientists have found that some sperm carries the X chromosome and some sperm
carry the Y chromosome, and an egg will always have an X chromosome, therefore
the answer is the sperm determines the human baby's gender.
If the sperm carrying an X chromosome fertilizes the egg, the baby will be a
girl, if the sperm carrying a Y chromosome fertilizes the egg, the baby
is a boy. The one cell embryo undergoes a series of cleavage divisions progressing
through two cell four -cell, eight - cell, sixteen -cell (the marula )stages, usually
reach blastocyst stage by day five after fertilization. The fertilized egg then
undergoes several divisions to form a multicelled blastocyst, it moves into the
uterus within a period of five to seven days, and is then termed as an embryo.
When the embryo implants in the uterus it secretes a hormone called human
chorionic gonadotropin HCG which helps maintain the pregnancy, this is the
hormone analyzed in the blood or urine to detect or confirm the pregnancy.
A blastocyst is an embryo which has developed to the point of having two different cell components
and a fluid cavity, usually reach blastocyst stage by day five after
fertilization. Embryonic stem cells are the cells within the protective layer of
the blastocyst known as inner cell mass.
Embryonic stem cells have the ability to self-renewal to generate duplicate
multipotent copies of themselves. The embryo the stem cells are capable of
becoming all of the various cell types of the human body, such as muscle cells
nerve cells and many other cell types. It is hard to believe, just 10 days after
implantation is complete, the embryos heart begins to beat!
Once implantation is complete the embryo continues to grow inside the wall of the
uterus, the placenta which will nourish the baby also starts to form.
On an ultrasound scan of ten weeks the fetus can move and jump inside the womb. This is an amazing story of egg and sperm during human development.
A human egg is remarkably big can actually be seen with the naked eye and
16 times bigger than a sperm. The egg has a short life after released from the
ovary it lives about 24 hours if the egg is not fertilized by a sperm. The fusion
of sperm egg produces the first stem cell, zygote in human body.
Hi, I am a zygote, thanks for watching.
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