Spermatogenesis VS Oogenesis

 Get
out homework (phases of meiosis
 Fill in Meiosis Mitosis Venn Diagram
Please try to think of at least four differences for
each and two things they have in common
How meiosis is different in males and females.
 Meiosis
in males, process used to create sperm
 Males create four sperm cells for each single
 Remember the original spermatogonium is diploid,
while the resulting four sperm are
haploid (have half the DNA)
 This process
occurs in the
tubules which make up
the testes
 Seminiferous
tubules are the
little tubes that curl around
to create the testes
 If stretched out these could
reach 300 to 350 meters
 Men can produce an infinite
number of sperm in their life
 They begin producing sperm
at puberty because that is
when the tubes become
 The
starts on the outside
of the tube
 As it moves its way
to the inner portion
of the tube it
undergoes meiosis
 The four sperm are
then released into
the inside of the
seminiferous tubule.
 Oogenesis
is meiosis in
females and produces
one egg cell.
 Each round of meiosis
creates one mature
egg cell that can be
fertilized and three
polar bodies, which
cannot be fertilized.
 This process occurs in
the follicles of the
 Each
female has
about 400,000
primary follicles
in her ovary at
 A female starts producing egg cells at puberty and cannot
possibly produce more egg cells than she has follicles
 Most female produce about 400 mature eggs in her
 During ovulation the egg is released from the ovary so it
can be fertilized
Creates four mature
Occurs continuously
 Occurs throughout
entire life after
 Occurs in males
 Sperm are smaller
and motile
Creates one mature
egg and three polar
 Occurs once a month
 Stops occurring once
menopause is reached
Occurs in females
 Egg is much larger
and not motile
 Both
are forms of meiosis
 Both create sex cells used in sexual
 Both occur in the gonads
 Both start with a diploid cell and end up with
haploid cells.
 Both occur in plants (pollen or spores and
egg instead of sperm and egg) and animals
Most issues during gamete
formation occur during meiosis I
 As a woman gets older there
become more and more genetic
abnormalities in her eggs, which is
why the chances of bearing a child
with birth defects increase as a
woman gets older.
 Sometimes during meiosis the
chromosomes do not separate
causing the egg or sperm to either
have 46 or 0 chromosomes
 Sometimes only one pair of
chromosomes does not separate
causing the egg or sperm to have
47 or 45 chromosomes.
 Sometimes
sperm do not
form properly
 When this occurs it can
lead to infertility
 Even though sperm are
being produced, they might
be slow or not motile.
 This causes them to die
before they could possible
reach the egg