I Oogenesis stages
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• The process of oogenesis passes through three important stages, which are as follows :
•This stage occurs during the
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development of the female
embryo, where:
- Mitotic division of the primary
Multiplication
stage:
germ cells (2n) takes place .
- This div ision results i n the
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oogonia (2n).
•This stage occurs during the female
embryo development, where:
The oogonia (2n) store an
amount of food, therefore they
into primary oocytes (2n) .
(2n) are divided by
meiosis
- Secondary oocyte (n).
The secondary oocyte
is larger than the polar
body, as it contains the
Maturation
stage :
stored food.
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Secondary
oocyte (n)
(I), giving:
- Polar body (n) .
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Primary oocyte
(2 n)
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i ncrease in size and transform
•The primary oocytes
Mitotic
division
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formation of cells called
Growth stage :
Primary germ
cell (2n)
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Polar body
(n)
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Ovum (n)
(n)
d;
•The secondary oocyte (n) is divided by meiosis (II), giving:
- Ovum (n) .
- Polar body (n) .
And meiosis (II) occurs in the fallopian tube once the sperm
penetrates the ovum to accomplish the ferti I ization ( i .e . it is
a delayed or conditioned division).
•Meiosis (II) occurs to the polar body (n), giving two polar bodies
(and so the total number will be three polar bodies).
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