Transcript (1 to 2 weeks) it is called an embryo.

Ms. Kehoe
9th Grade Health
Fertilization Process
• Foreplay hugging, kissing, caressing to get the person
sexually aroused - the male gets an erection and the
female vagina lengthens, widens & moistens, Skene's
Glands & Bartholin's Glands
• Ejaculation: when the man reaches orgasm he
ejaculates up to 500 million sperm inside the woman, usually
around the cervix.
• Within hours many sperm make their way into the woman’s
body with only a few hundred make their way into the
fallopian tubes.
• The female does not have an ejaculation, she may
experience orgasm but not necessarily at the same time as
the male. She does not release an egg cell when she has an
orgasm but she may become moist.
• If no egg is present in the fallopian tubes the sperm will die
in a few days.
• If an egg is present in the fallopian tubes fertilization may
take place.
Fertilization Process
Egg (ovum) is released into the fallopian tube.
Sperm surround the egg.
Sperm surround the egg – releasing enzymes to
break down the protective cells surrounding the
mature egg.
Only the head of one sperm enters the egg. No other
sperm may enter because the egg cell’s outer
membrane changes sealing out all other sperm.
The two nuclei (sperm and egg cell)
combine .
The Two Nuclei Combine 23 chromosomes from the male and
 23 chromosomes from the woman
 Combine to form 23 pair or 46
chromosomes.
Chromosomes
 Are thread-like structures in the nucleus of the cell
that are made up of genes,
 Carries of hereditary traits,
 That determine which traits we inherit from out
parents
Sex of the Child
 Egg has a X chromosome pattern gene
 Sperm has a X or Y chromosome
pattern gene
 XX chromosome pattern will be a girl
 XY chromosome pattern will be a boy
 Current theory is the sperm
determines the sex of the child
Development of a
Human Being
Within the first 36 hours the fertilized egg
(zygote) cleaves (divides) forming two identical
connected cells.
4 Cells,
8 cells, 16 cells, ...
..until a hollow ball of cells is
formed (blastula)
Fraternal Twins: 2 eggs are released and
fertilized.
Identical Twins: 1 egg & 1 sperm divide into two
separate morula.
Once the blastula is implanted in the
uterus
(1 to 2 weeks) it is called an embryo.
Development of a Human
 Within the first 36 hours the fertilized egg
(zygote) cleaves (divides) forming two identical
connected cells, 4 cells, 8 cells, 16 cells, until a
hollow ball of cells is formed (blastula). Once the
blastula is implanted in the uterus (1 to 2 weeks) it
is called an embryo. This cleaving process will
continue for the next 9 months.
Super Structures
Yolk:
 looks like the yellow part in an egg – it provides
nourishment for the embryo until the placenta is
developed.
Stalk:
 Holds the
embryo to
the uterine
wall and
becomes the
umbilical
cord.
Umbilical Cord
 – rope like structure
–width of your
thumb,
 14 to 30 inches long,
& all nourishment
and waste pass
through this
structure.
 It has no nerves so it
causes no pain when
it is cut.
Umbilical Cord:
Placenta:
 Network of blood
vessels and other
tissues which is
attached to the wall of
the uterus.
 It serves as transition
place for all
nourishment & waste.
 The blood of the
mother and the fetus
never mix.
Placenta Cont.:
 The blood vessels grow side by side and are not directly
connected.
 Blood type of the fetus can be different from that of the
mother.
Development of a Human
Being Terms:
Amnionic Sac:
 Fluid filled membrane
that surrounds the
growing embryo and
fetus.
 Called the bag of
water.
 Functions: controls
temperature, provides
room to grow and
move, and protects
the fetus from injury.
Zygote:
 a fertilized egg (ovum)
Blastula:
 A hollow ball of
cells that divides as it
travels to the uterus.
 It gets its
nourishment from
the blood enriched
walls of the womb.
Embryo:
 Implanted
blastocyst in the
uterus.
Fetus:
From the 10th
week until the
birth .
Looks like a tiny
human being.