Chapter 1- Basic mechanism of

sexual reproduction
 What do we need for sexual
reproduction???
Female reproductive system Male reproductive system

By meiosis

Female gamete= ovum Male gamete= sperm cell

By fertilization

Zygote then embryo then a new born

 Activity 1- male and female
reproductive system
What is the function of a reproductive system?

It is a set of organs that ensure reproduction,

that involves two individuals of opposite sex and belonging to the
same species.

How can reproductive systems ensure their function?

 By producing:

Gametes Sexual hormones

Female gamete Male gametes Female hormones Male hormone

Oocyte II Spermatozoon (zoa) Estrogen and Testosterone

or progesterone
sperm cell (s)
 Oocyte vs sperm cell

Question: Make a comparative table showing 3 differences between

sperm cell and oocyte showing shape, relative size and motility
Title: table showing 3 differences between sperm cell and oocyte showing
shape, relative size and motility

Male gamete Female gamete

Shape Elongated shape Rounded shape
Relative size Smaller in size Larger

Motility Motile Relatively immotile

 The male reproductive system page 18 in the book
Read the next document then answer
the following questions
• Name the fluid ejaculated by the
male during sexual intercourse.
• The male releases by ejaculation a
white fluid called semen.
• What does semen contain?
• It contains sperm cells suspended in a
fluid called seminal fluid.
• What is the importance of seminal
fluid?
• The seminal fluid contains fructose
and other nutrients that ensure the
survival and the motility of
spermatozoa.
 The male reproductive system Document a page 18 in your book

Ureter
Accessory glands

Urinary bladder
Seminal vesicle
Vas deferens or spermiduct
Prostate
Urethra Or urogenital tube
Bulbo-urethral gland
(Cowper’s gland)

Epididymis
Testis
Urogenital-
Scrotum
opening

Duct = tube
 Label the following

Seminal vesicles
Prostate
Cowper’s gland

Epididymis

Testis

Draw a concept map showing the pathway of the sperm cell through the male
reproductive tract, from their production site till their ejaculation.

Testes Epididymis Vas deferens Urethra Urogenital opening

Title: concept map showing the pathway of sperm cells…

Draw a map showing the organization of the male reproductive
system

two gonads = testes

Epididymis
Genital tract Spermiduct or vas deferens
The male
reproductive urethra
system
Seminal vesicles
Three Accessory glands
Prostate

Bulbo-urethral gland

Copulatory organ Penis

Title: map showing the organization of the male reproductive system
 Semen = sperm cells + seminal fluid

What is the origin of:

1- Sperm cells? Sperm cells are produced by the seminiferous tubules of the testes.

2- seminal fluid? The seminal fluid is secreted by the 3 accessory glands: seminal vesicles
Prostate and Cowper gland.
Maturation and storage of
spermatozoa and acquiring motility
 The female reproductive system

Ovaries

Genital tract (duct)

Fallopian tube or Oviduct
Uterus
Cervix

Vagina
Urinary
bladder
Urethra

vulva
Genital
opening

Anatomy of the female reproductive system (Side view)

Anatomy of the female reproductive system (front view)

Define ovulation? Ovulation: is the release of the oocyte II from

the ovary to the oviduct.
Indicate the function of each organ:
Draw a map showing the organization of the female
reproductive system

two gonads = ovaries

Fallopian tubes or oviduct

Genital tract Cervix
The male
reproductive Vagina
system
Uterus

Copulatory organ Vagina

Title: map showing the organization of the female reproductive system

Page 19 in your book
Draw a comparative table showing the differences between the genital activity of
the male and female.

Male genital activity Female genital activity

It is continuous It is cyclic (variable once each 28 days)
and interrupted by pregnancy (or
gestation).
It remains continuous till death decreasing It stops at menopause (45- 50 years)
gradually
 What happens in the ovary during
each menstrual cycle??
Ovulation day
Preovulatory phase Post ovulatory phase

24 Hours after the day 14

The oocyte II The oocyte II may be
Few hours
Many oocytes I Before the is released
Try to mature ovulation from the
Day one ovary to Fertilized before Not fertilized
the 24 hours from
becomes an ovulation
Oocyte II oviduct
The oocyte II
A zygote is formed degenerates
 Activity 2 diploid and haploid cells

You should:
1- write the chromosomal formula of a karyotype.
2- compare 2 karyotypes.
3- Identify the diploid and haploid cell.
4- know the three types of cells.
Karyotype of Karyotype of
a a
female male

There are 2 types

of chromosomes What do we call the chromosomes of each pair?
Autosomes : common for
male and female from 1 to 22 The homologous chromosomes :
1- are the chromosomes of each pair.
Gonosomes= sex chromosomes 2- they are genetically different because
the 23rd one that are X and Y (Y is one of maternal origin while the other of
shorter than X) paternal origin.
The characteristics of a karyotype

• The total number of chromosomes

• The chromosomes are duplicated or non- duplicated.
• The chromosomes exist in pairs (=2 examples) or in one
example.
• The sex chromosomes = gonosomes.
 Compare the following karyotypes
Compare= similarities + differences in
a paragraph

Both karyotypes consist of same

number of chromosomes = 46 that
are duplicated and exist in pairs,
however, the gonosomes are XY
in the first karyotype while XX in
the second
 Write the chromosomal formula of:

(46, XX) or (44+ XX) (46, XY) or (44+ XY) (23,X) or (22+ X) (23,Y) or (22+Y)
 Diploid and haploid cells

• If in a cell the chromosomes exist in pairs thus

it is a diploid cell.
• And it is represented by 2n.
• If in a cell the chromosomes exist in one
example, thus this is a haploid cell.
• And it is represented by n.

• Examples
 Haploid

Diploid

Haploid

Question :Verify whether these karyotypes correspond to haploid or diploid cell

In karyotype 1 and 3, since the chromosomes exist in one example and knowing
that only haploid cells have chromosomes in one example thus they
are haploid.
In karyotype 2, since the chromosomes exist in 2 examples and knowing only
diploid cells have the chromosomes in pairs, thus the cell is diploid.
 What are the 3 types of cells in our
body???
• Somatic cell: is the body cell (skin cell, neuron,
muscle cell…). (2n)
• Gametes or germ cells: sperm cell (male gamete)
and the oocyte II (the female gamete). (n ch)
• Germ stem cells: the diploid cell from which
gametes are produced in the gonads. (2n)
• The male germ stem (spermatogonium) cell
produces the sperm cells.
• The female germ stem cell (oogonium) produces
the female gamete (oocyte II).
 Cells Chromosomal formula
Male somatic cell (46, XY)
Female somatic cell (46, XX)
Male germ stem cell (46, XY)
Female germ stem cell (46,XX)
Female gamete (23,X) or (22+X)
Male gamete (23, X) or (23,Y)
 Chapter 1 activity 3-
Meiosis
Objectives: Definition, aim, phases,
chromosomal behavior during
meiosis
What is meiosis and why do we need it???
• We know that:
• male germ stem cell  sperm cells
• Female germ stem cell  oocyte II
• 2n n
• Definition: it is a cell division that produces 4 haploid cells
from one diploid cell.
• These haploid cells are incapable of any further division.
• Aim of meiosis: it is a main step of gametogenesis
• production
• It needs a (one) preparatory step called “Interphase”.
• What for??
 Each cell division, meiosis or mitosis is
preceded by one and only one interphase
• Interphase consists of 3 phases:
• G1 S G2
• G1 and G2 are growth phases where the cell
only grows and may increase in size.
• S= synthesis phase, during which DNA
duplicates (or replicates).
• Question: Represents these phases in a
chromosomal diagram.
 Chromosomal diagram of meiosis and interphase

Meiosis consists of 2
successive divisions:

Interphase
DNA duplication 1- first meiotic division or
reductional division.
Separation of
homologous Reductional division
chromosomes 2- second meiotic division
or equational division
Separation
of sister Equational division
chromatids
 Fill in the following comparative table
Reductional division Equational division
There is separation of Homologous chromosomes Sister chromatids
The number of
chromosomes Is reduced into the half Remains the same n ch
From 2n to n
The quantity of DNA Reduced into the half Reduced into the half

4 phases

Reductional Prophase I, metaphase I,anaphase I then

Meiosis division telophase I
consists of Equational Prophase II, metaphase II, anaphase II then
division telophase II
The phases of meiosis of a cell with
2n= 4 ch (2 pairs of chs)
 The phases of meiosis of a human cell
2n=4ch (2 pairs of chromosomes)
Centrioles or centrosome
chromatin
Nucleolus

At the end of interphase

Prophase I
1- nuclear membrane and nucleolus disappear.
5- pairing of homologous chromosomes
2- Spindle fibers appear. forming tetrads.
3- The 2 asters are formed
6- crossing over.
4- The chromosomes condense
becoming visible.
 What is Crossing-over?

Definition: it is the exchange of DNA fragments between non-sister chromatids of

homologous chromosomes during prophase I only.
 Diploid set of chromosomes
n ch

n ch

Reductional division
Telophase I
Metaphase I 1- the nucleoli reappear. Also the
1- The 2 asters occupy the opposite poles nuclear membrane
2- homologous chromosomes occupy the
same fiber, forming the equatorial plate. 2- Cytoplasmic constriction appears
Dividing the cell into 2 daughter cells.
Anaphase I
1- separation of homologous chromosomes 3- each daughter cell contains
that migrate towards opposite poles half number of chromosomes (n ch)
(polar ascension). that are duplicated.
Thus 2 haploid cells are formed.
 Equational division

n ch

Prophase II Anaphase II
- The 2 asters appear. 1- separation of sister chromatids.
- The nucleolus disappears. 2- polar ascension.
(at each pole there is a set of
Non-duplicated chromosomes.
Metaphase II
1- the two asters occupy Telophase II
the opposite poles 1- also a cytoplasmic constriction appears
2- each chromosome binds Dividing each one into 2 daughter cells.
to one fiber, forming the 2- the nuclear membrane and nucleolus reappear.
equatorial plate. 3- aster becomes centrioles.
Chromosomes decondense into chromatin
 Metaphase I Metaphase II
The Haploid set
equatorial Diploid set of of
plate consists chromosome chromosome
of s s
On each fiber A pair of Only one
there is homologous chromosome
Metaphase II Metaphase I chromosome
s

Anaphase I Anaphase II
Separation of Homologous Sister
chromosomes chromatids
At each pole Haploid set of haploid set of
there is duplicated non-
chromosomes duplicated
chromosomes

Anaphase I Anaphase II
Variation of the quantity of cellular
DNA during meiosis Page 23

G1 2n

G2
2n n
n

Equational division
Reductional division
Explain the evolution (variation) of the quantity of DNA/cell in document c page 23 in your
book.
[Explain = analyze each variation then explain it using your acquired knowledge.]
Answer:
As time (in days) passes from 0 till 21, the amount of DNA/cell remains constant = q au. Because
this is the G1 phase of interphase during which the number of chromosomes remains 2n and non
duplicated. While as time increases till 25 days this amount increases till becoming 2 times greater
= 2q au due to the DNA duplication where the chromosomes become duplicated but still 2n.
however as time passes till 26 au this amount remains constant 2q au because this is the G2 phase
of interphase where the chromosomes remain 2n and duplicated. Moreover the quantity remains
constant as time continues passing till 30th day because it corresponds to prophase I then
metaphase I then anaphase I and the chromosomes are still 2n and duplicated till metaphase I.
while at 30th day this amount decreases till becoming the half = q au due to the separation of
homologous chromosomes during anaphase I followed by the division of the cell into 2 daughter
cells in telophase I where each cell is now haploid n=23 ch but still duplicated. Moreover this
amount remains constant q au as time passes till 32 days because this prophase II, metaphase II of
equational division where the cell is haploid with duplicated chromosomes. On the other hand at
the 32nd day the amount of DNA/cell decreases till the half q/2 au because after the separation of
sister chromatids during anaphase II, each of the 2 cells divides by telophases II into 2 daughter
cells with n ch but non duplicated this remains the same till the 52nd day.
Activity 4 spermatogenesis

1- Histology of the testis.

2- Spermatogenesis steps,site and
duration
 1- Histology of the testes
What does each testis contain?
Each testis consists of many lobules (2---300), where each lobule contains 1-4 tightly
coiled tubules called seminiferous tubules which produce spermatozoa.

What is spermatogenesis?
- It is the production of sperm cells from
- male germ stem Cells = spermatogonia inside
the seminiferous tubules of the testes.
- It starts at puberty.
For how long does a spermatogenesis cycle last?
A Spermatogenesis cycle lasts for 74 days
(2 months and a half)
What are the steps of spermatogenesis?
Spermatogenesis consists of 4 steps:
1- multiplication= mitosis many times.
2- growth.
3- maturation = meiosis.
4- differentiation = spermiogenesis.
 The anatomy of the sperm cell
- The sperm cell consists of three different parts: Acrosome
Nucleus

Head
Head Mid piece Flagellum Cytoplasm
Proximal
Indicate the function of: centriole
Distal centriole

Mid piece
Function
Bundle of
Acrosome It is a vesicle found in front of the microtubules
nucleus. It contains hydrolytic enzymes
that digest the layers surrounding the Helix of mitochondria
oocyteII during fertilization

Mitochondria produce energy that is necessary

for the motility of the sperm cell.

Flagellum
Protein sheath
Flagellum Ensures the motility of the sperm
cell.
 Chromosomal diagram showing the steps of spermatogenesis

Spermatogonium
2n
1- Multiplication
Spermatogonia
2n 2n 2- Growth=
Interphase
Spermatocyte I
1st meiotic
2n division
Spermatocyte II n 3- Meiosis or maturation
n 2nd meiotic
division
Spermatid
n n n n
Differentiation or
n n n n spermiogenesis
Sperm cell
Spermiogenesis: or differentiation: is the set
of cytoplasmic transformations of the
rounded spermatids into sperm cells.

What happen during spermiogenesis?

During spermiogenesis:

1- the Golgi body transforms into acrosome.

2- The distal centriole forms the flagellum.
3- the mitochondria form a helix around the
flagellum forming the mid piece.

Once the sperm cells are formed, they are

released from the sertoli cell into the lumen
of the seminiferous tubule
List the steps of spermatognesis
1- in the seminiferous tubules of the testes, The
spermatogonia divide by mitosis many times
producing many identical spermatogonia (2n)

2- Each spematogonium duplicates its DNA and

increases in size to become spematocyte I (2n)

3- Each diploid spermatocyte I divides by 1st

meiotic division into 2 haploid spematocyte II ,
after the separation of the homologous
chromosomes.
Then these two spermatocytes II divides by 2nd
meiotic division to produce 4 haploid
spermatids after the separation of sister
chromatids.

4- each spherical and haploid spermatid undergoes some

structural modifications to become an elongated sperm
cell that is still haploid. These mature sperm cells are now
free in the lumen of the tubules.
Spermatogenesis in the seminiferous tubules occurs in a centripetal direction,
from the basal lamina towards the lumen.
 Inside the testis there are 2 somatic cells: Sertoli cells and Leydig cells

Comparative table between Sertoli cell and Leydig cell showing the differences:

Sertoli cell Leydig cell

Location Inside the seminiferous Between the seminiferous
tubules tubules

1. Ensures the
Are endocrine cells
Function centripetal direction
that Secrete the male
of the
hormone, testosterone
spermatogenesis.
directly in the blood
2. Provides the sexual
cells with their
nutritive needs.
Answer:
A=
spermatogonium
b= spermatocyte I
c= spermocyte II

D= spermatids ,

e= sperm cell
 Answer:
a. A= spermatogonium
B= spermatocyte I C= sertoli cell
D= spermatocyte II,
E= spermatid F= sperm cell.

a. The number of chromosomes in:

- spermatogonium and spermatocyte I, is 2n=46

- spermatocyte II, spermatid and sperm cell = n=23.

a. The biological process is spermatogenesis, it occurs in the seminiferous tubules of the

testes, its outcome is many sperm cells or spermatozoa.
 Chapter 1-Activity 5

Oogenesis and folliculogenesis

Anatomy of the ♀reproductive system
(front view)
Production of gamete by the female
Reproductive system

Ovulation: is the release of the

oocyte II from the ovary to the
oviduct.
 Oogenesis
Genesis= production
 Oogenesis
of Oogenesis
Aim To produce haploid female gamete = oocyte II from a diploid
germ stem cell called oogonium.
Location It starts in the ovaries (gonads)
4 stages:
Stages
Multiplication- > interphase->meiosis -> differentiation

That’s why meiosis is an important stage of oogenesis

Chromosomal Oogonium
2n (44+XX)
diagram of oogenesis
stages
The diploid oogonia divide many 1- Multiplication
Meiosis Times by mitosis to produce
identical oogonia (2n)

The oogonia grow and increase 2- Growth

In size becoming oocyte I (2n) Oocyte I (2n)
Oocyte I divides unequally
into one oocyte II (n) and First meiotic
division

3- Meiosis
First Polar body nch nch
Each oocyte II divides
Also unequally into one
Ootid (n) and second 2nd meiotic
polar body Ootid 2nd polar division
nch nch body
Ootid differentiates 4- Differentiation
Into ovum nch
 So is oogenesis continuous???
How many ovum is produced
from one oocyte I?

First arrest where

Oocyte I is blocked
at prophase I

Second arrest at oocyte II

Blocked at metaphase II
 Questions
• How many polar body (ies) does:
• An oocyte I have? No polar body because none of the meiotic divisions occurred
• An oocyte II? One polar body because only the first meiotic division has occurred
• An ootid? 2, because the second meiotic is accomplished
• Identify the next oocyte.
• Oocyte II blocked at
metaphase II because it has
One released polar body
which means that the first
meiotic division has finished.
 Identify each oocyte.

Oocyte II blocked at metaphase II

Because it has one polar body
meaning that only first meiotic
division is resumed. And it has
chromosomes on the equatorial Plate.

Ootid (or ovum)

Because it has 2 polar bodies

meaning that the second
meiotic division is resumed.
 Conclusions
• Oogenesis is not continuous but blocked twice:
• At oocyte I prophase I.
• At oocyte II metaphase II.
• Oogenesis produces only one ovum from one oocyte I.
• The release of the first polar body proves that the first
meiotic division is resumed. (the oocyte I is unblocked)
• The release of the second polar body means that the second
meiotic division is resumed (the oocyte II metaphase II is
unblocked).
• The oocyte II blocked at metaphase II is unblocked by the
penetration of the sperm cell (by fertilization).
What can you conclude?

- The oogenesis starts at fetal life

- It decreases starting from 7 months
of fetal life
- The oocytes are depleted at age of
50 years,
(menopause).
Oogenesis during the female life from
embryonic life till puberty
Few hours
Before the
ovulation day
Number decreases
(degenerate)
Preovulatory phase Postovulatory phase
 What happens in the ovary during
each menstrual cycle??
Ovulation day
Preovulatory phase Post ovulatory phase

24 Hours after the day 14

The oocyte II The oocyte II may be
Few hours
Many oocytes I Before the is released
Try to mature ovulation from the
Day one ovary to Fertilized before Not fertilized
the 24 hours from
becomes an ovulation
Oocyte II oviduct
The oocyte II
A zygote is formed degenerates
 Conclusion: list the events of ovarian
cycle.
• 0 till day14:
• Many oocyte I try to mature but, few hours before the day 14, only
one resumes the 1st meiotic division becoming oocyte II and
releases first polar body that starts the second meiotic division but
again it is blocked at metaphase II.
• At the day 14 (ovulation day): the oocyte II that is blocked at
metaphase II, is released from the ovary to be received by the
fallopian tube.
• From 14 till 28: there are 2 possible fates;
• The oocyte II can survive for 24 hours, if it is not fertilized it will
degenerate.
• If it is fertilized by a sperm cell, the oocyte II is unblocked resumes
the second meiotic division releases the second polar body then
becomes an ootid, a fertilized ovum then a zygote that becomes an
embryo.
 Folliculogenesis
• Objectives:
• Define folliculogenesis and follicle.
• Types of follicles.
• Folliculogenesis: definition and stages.
 What is folliculogenesis??

?
Def: it is the production of a mature follicle
 What is follicle?
• The oocyte I is not alone in the ovaries but
surrounded with somatic cells called follicular
cells.
• So a follicle= oocyte I + follicular cells.
• Thus where are follicles found?
• In the ovaries
What are the different types of the follicles
that are found in the ovaries?
Tertiary or
Cavitary follicle
Secondary
follicle Cavity
Theca cells
Primary
follicle
Primordial
follicle

Mature or
Graafian
follicle
 The Graafian follicle
Cumulus oophorus
Zona pellucida Oocyte I (prophase I)

Theca externa
Corona radiata

Cavity or Antrum

Theca interna or Granulosa cells

Internal theca
 What is folliculogenesis??
Def: it is the developmental cycle of follicular cells to produce one
mature follicle
 What is folliculogenesis??
Def: it is the developmental cycle of follicular cells.

7- Ruptured
follicle
9- Corpus
albican

To the oviduct
8- Corpus luteum
ovulation
Folliculogenesis during the female life
 During each menstrual cycle
Oocyte I Few hours
Prophase I Day 10 before day 14
Luteal phase
Follicular phase
Oocyte I
Prophase I Corpus albican
The yellow body if:
1 Graafian Graafian follicle The No fertilization,
About 10 Bursts releasing
( ) ruptured Degenerates into
Cavitary The oocyte II =
follicle follicules= White body at the
follicles ovulation end
is formed (The
(Containing Of the cycle.
remaining
Oocyte I Graafian Follicle follicular
Blocked at with oocyte II There is fertilization:
Cells)
prophase I) At metaphase II The corpus luteum
transform
to mature Releasing the Is maintained for 3
into
first polar body yellow Months of pregnancy
by resuming the body Due to the HCG
first meiotic Of the embryo
division
 Activity 6- fertilization
Definition: it is the union of a female gamete with a male gamete to
produce a diploid cell (the zygote).
 Activity 6- Fertilization
• Definition: it is the union of a female gamete
with a male gamete to produce a diploid cell (the
zygote).
• The sperm cells acquire their ability of fertilizing
the oocyte II during their passage in the female
reproductive tract= capacitation.
• Capacitation involves biochemical changes of
the sperm cytoplasmic membrane.
• The sperm cell can survive for about 72 hours in
the female genital tract.
Label the following
• 1- corona radiata.
• 2- 1st polar body.
• 3- chromosomes
at the equatorial
plate.
• 4- zona pellucida
• 5- perioocytar
space.
• Cortical granules.
The oocyte II with its corona radiata is
released towards the oviduct

Follicular cells of the corona radiata

Cytoplasmic membrane

Cortical granules

Zona Pellucida

Perioocytar space

First polar body

Cytoplasm
 What is the importance of?
(Page 29 in the book)
• Meiosis? • Fertilization ?
• To produce haploid cells • To return to the diploid
= gametes from diploid state.
cells.
 Fertilization

Release of the
second polar body

Release of the first polar body

Multiplication Growth

Reductional division and

part of equational division