Female Genital System
1. Primary sex organs: 2 ovaries
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Attached to the back of the broad
ligament of the sides of the uterus.
Each ovary is almond shaped
It consists of small vascular medulla
surrounded by a thick cortex covered
by cuboidal germinal epithelium.
Function: formation of ova &
female sex hormones (oestrogen
& progesterone).
2. Genital ducts:
a) Uterus:
 It is a muscular organ that
consists of fundus, body
& cervix.
 The cavity of the uterus is
continuous below with the
cavity of the cervix (cervical
canal) at the internal os.
b) Uterine (Fallopian) tubes:
 2, their lateral fimbriated ends
open into the peritoneal cavity
close to the ovaries. Their
medial ends open in the uterus.
c) Vagina:
It is a muscular tube that
connects the external genital
opening with the lower
opening of the cervical canal
(external os).
3. External genitalia
Oogenesis
Definition:
 It is the process by which the oogonia
(primordial germ cells )are transformed into
mature ova ( gamete ).
Unlike the male, maturation of the female gamete
begins before birth (third prenatal month).
 Site: It occurs in the cortex of the ovary.
 STEPS:
 The total number of female germ cells by the 5th
prenatal month reaches about 7 million.
 The majority of oogonia divide by mitosis and
some divides by meiosis but are arrested in
prophase of MI as primary oocytes.
Most of the cells became atretic (dead).
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At birth the total number of primary oocytes is about 2
million and all are arrested in the prophase of MI.
 Each primary oocyte is surrounded by a layer of epithelial cells
(follicular cells) and is known as a primary follicle.
Oocyte maturation inhibitor (OMI) is a substance secreted by
follicular cells that arrest the primary oocytes in MI.
 During childhood most oocytes became atretic and at
puberty the number is 400,000 of which 500 will continue to
ovulation.
 At puberty a large number of primordial follicles are present.
Each month, 1 5 to 20 follicles are selected to start
maturation.
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Stages Of Oogenesis Maturation
) Primary or preantral stage.
2) Secondary or antral stage (Graafian).
3) Preovulatory stage.
Oogonia:
 Lie in the cortex of the ovary.
 Each contains 44 autosomes and 2 X- chromsosomes.
 The oogonium enlarges to form the primary oocyte.
 Each primary oocyte is surrounded by a single layer of flat
cells to form the primordial follicles.
1
Preantaral Stage:
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As the 1ry oocytes begins to grow, the surrounding follicular
cells change from flat to cuboidal to stratified epithelium of
granulosa cells forming 1ry follicle.
Granulosa cells rest on a basement membrane separating
them from the surrounding stromal cells that form the theca
folliculi.
The granulosa cells and the oocyte secrete the zona
pellucida (a layer of glycoproteins on the surface of the
oocyte).
The cells of the theca folliculi organize into an inner layer of
secretory cells, the theca interna and an outer fibrous capsule,
the theca externa.
Antaral Stage:
The antral stage is the longest stage.
 As development continues, fluid-filled spaces appear
between granulosa cells which unite together leading to
antrum formation.
 The follicle at this stage is termed 2ry follicle (Graafian
follicle).
 The antrum is firstly
crescent shaped and
then it enlarges.
Granulosa cells surrounding the
oocyte remain intact and form
the cumulus oophorus.
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With each ovarian cycle, a number of follicles begin to develop,
but only one reaches maturity and the others degenerate.
Preovulatory Stage:
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It takes place 37 hours before ovulation.
It is induced by the effect of Luteinizing hormone (LH)
2. The primary oocyte (44+2X):
Enters the prophase of first meiotic division at the 3rd
intrauterine foetal month.
It completes first meiotic division few hours before
ovulation to form two haploid cells.
(a) A large cell called secondary oocyte.
(b) A small cell called first polar body.
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One cell, the 2ry oocyte receives most of the cytoplasm; the
other, the first polar body, receives practically none.
The first polar body lies between the zona pellucida and
the cell membrane of the 2ry oocyte.
 Then the cell enters M II, but arrested in metaphase
three hours before ovulation.
 Meiosis II is completed only if 2ry oocyte is
fertilized, otherwise the cell degenerates 24 hours after
ovulation.
Secondary oocyte ( 22+X):
Undergoes the 2nd meiotic division to form two cells:
(a) A large cell called mature ovum.
(b) A small cell called second polar body.
This division occurs in the uterine tube and is not
complete until after fertilization has taken place.
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Structure of Graafian follicle (1/2 cm in diameter):
1. Secondary oocyte (120µ in diameter) surrounded by:
a) the cell membrane of the 2ry oocyte.
b)Zona pellucida :non-cellular glycoprotein coat.
c) Corona radiata : single layer cells surrounding the
zona pellucida.
2. Stratum granulosum: the outer wall of follicle, made of
follicular cells.
3. Antrum = the cavity of follicle, filled with liquor folliculi.
4. Cumulus oophorus = group of follicular cells attaching
the 2ry oocyte to one side of the antrum.
The compressed ovarian stroma forms a capsule around
the follicle called Theca Folliculi which is divided into:
1) Theca externa: mostly cellular.
2) Theca interna: mostly vascular.
A.Preovulatory follicle bulging at the ovarian surface.
B. Ovulation. The oocyte, in metaphase of meiosis II, is discharged from
the ovary together with a large number of cumulus oophorus cells.
Follicular cells remaining inside the collapsed follicle differentiate into
lutean cells.
C. Corpus luteum. Note the large size of the corpus luteum, caused by
hypertrophy and accumulation of lipid in granulosa and theca interna
cells. The remaining cavity of the follicle is filled with fibrin.
Events occurring during the first and second maturation divisions.
A. The primitive female germ cell (primary oocyte) produces only
one mature gamete, the mature oocyte.
B. The primitive male germ cell (primary spermatocyte) produces
four spermatids, all of which develop into spermatozoa.
Differences between Spermatogenesis & Oogenesis
Spermatogenesis
(1) One primary spermatocyte
gives four mature
Oogenesis
(1) One primary oocyte gives
only one Mature gamete
(ovum)
(2) Maturation of sperms takes
place continuously
(2) Usually one ovum matures
every month
(3) The cytoplasm is reduced in
the male gamete because during
the cell division the cytoplasm is
equally distributed between the
daughter cells
(3) The cytoplasm is increased
in the female gamete because
during the cell division almost
all cytoplasm goes to the
daughter cell which will form
the mature ovum
Differences between Spermatogenesis & Oogenesis
Spermatogenesis
Oogenesis
4)A mature sperm is produced in
about 2 months.
In a female, a primary oocyte may
wait up to 45 years before
complete maturity. complete
maturation of the female gamete
is dependent on fertilization by a
mature sperm.
(5) Begins at puberty and
continues to very old age.
(4) Begins at 3rd prenatal month
but formation of mature ova
occurs from puberty to
menopause
(5) Number: one ovum is
produced every a lunar month,
(6) Number: 200-300 million of
sperms are ejected in each
ejaculation.