Menstruation is the shedding of the uterine lining
(endometrium). Once a girl hits puberty(usually
starting between ages 8 and 13) it occurs on a
regular basis. About once a month, an egg leaves
from one of the ovaries this process is called
ovulation. The egg travels down one of the
fallopian tubes toward the uterus. Days before the
egg leaves the ovaries the uterus builds up its
lining with blood and tissue.
If the egg is fertilized by sperm cell , it travels to the
uterus and attaches to the cushiony wall of the
uterus and grows into a baby. But if the egg is not
fertilized witch is the usually the case during a
woman’s monthly cycle it does not attach to the
uterus wall and the uterus sheds the blood and
tissue lining. The blood tissue and unfertilized egg
leave the uterus going through the vagina on the
way out of the body.
This cycle usually lasts for 3 to
7 days a month and will keep
happing for several more
years until the woman reaches
menopause and will no longer
release eggs from her ovaries.
Next Spermatogenesis
Spermatogenesis is the process by which male
primary germ cells undergo division, and
produce a number of cells called
spermatocytes, from which the primary
spermatocytes are derived. Each primary
spermatocyte divides into two secondary
spermatocytes, and each secondary
spermatocyte into two spermatids or young
spermatozoa. These develop into mature
spermatozoa, also known as sperm cells. The
primary spermatocyte gives rise to two cells,
the secondary spermatocytes , and the two
secondary spermatocytes by their subdivision
produce for spermatozoa.
Spermatozoa are the mature male gametes
in many sexually reproducing organisms.
Spermatogenesis is the male version of
gametogenesis. In mammals it occurs in
the male testes and epididymis in a
stepwise fashion, and for humans takes
approximately 64 days. Spermatogenesis is
highly dependent upon optimal conditions
for the process to occur correctly, and is
essential for sexual reproduction. It starts
at puberty and usually continues
uninterrupted until death , although a
slight decrease can be discerned in the
quantity of produced sperm with increase
in age. The entire process can can be
broken up into several distinct stages, each
corresponding to a particular type of cell.
Fertilization is when the egg is
released from the ovary. The egg
travels to the fallopian tube. The
sperm that has been ejected into
the vagina swim into the opening of
the cervix and up along the uterus
and toward the egg in the fallopian
tube. When the sperm meet the egg
one sperm will penetrate into the
egg. This process is called
conception. After the egg attaches
to the uterus it starts breaking up
into tiny cells to make a baby.
http://deerparkhpe.wikispaces.com/7-1+HEALTH+2010-11
http://kidshealth.org/teen/sexual_health/girls/menstruation.html
http://womenshealth.about.com/od/menstruation/Menstruation.htm
http://www.embryology.ch/anglais/cgametogen/spermato01.html
http://www.britannica.com/EBchecked/topic/559418/spermatogene
sis
• http://www.britannica.com/EBchecked/topic/559418/spermatogene
sis
• http://www.hc-sc.gc.ca/index-eng.php
• http://www.google.ca/
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