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● Male main reproductive organs.
● Female main reproductive organs.
● Male hormones.
● Female hormones.
● Infertility in both men and women
● Vitro Fertilization
The Male Reproductive System
The purpose of the organs of the male reproductive system is to perform the
● To produce, maintain, and transport sperm (the male reproductive cells)
and protective fluid (semen)
● To discharge sperm within the female reproductive tract during sex
● To produce and secrete male sex hormones responsible for maintaining
the male reproductive system
Unlike the female reproductive system, most of the male reproductive system
is located outside of the body. These external structures include the penis,
scrotum, and testicles.
Organs of the Male Reproductive System
● Testicles (testes): These are oval organs about the size of
large olives that lie in the scrotum, secured at either end by a
structure called the spermatic cord. Most men have two testes.
The testes are responsible for making testosterone, the primary
male sex hormone, and for generating sperm. Within the testes
are coiled masses of tubes called seminiferous tubules. These
tubes are responsible for producing sperm cells.
● Scrotum: This is the loose pouch-like sac of skin that hangs behind and
below the penis. It contains the testicles (also called testes), as well as
many nerves and blood vessels. The scrotum acts as a "climate control
system" for the testes. For normal sperm development, the testes must
be at a temperature slightly cooler than body temperature. Special
muscles in the wall of the scrotum allow it to contract and relax, moving
the testicles closer to the body for warmth or farther away from the body
to cool the temperature.
● Epididymis: The epididymis is a long, coiled tube that rests on the
backside of each testicle. It transports and stores sperm cells that are
produced in the testes. It also is the job of the epididymis to bring the
sperm to maturity, since the sperm that emerge from the testes are
immature and incapable of fertilization. During sexual arousal,
contractions force the sperm into the vas deferens.
● Vas deferens: The vas deferens is a long, muscular tube that travels
from the epididymis into the pelvic cavity, to just behind the bladder. The
vas deferens transports mature sperm to the urethra, the tube that
carries urine or sperm to outside of the body, in preparation for
● Ejaculatory ducts: These are formed by the fusion of the vas deferens
and the seminal vesicles (see below). The ejaculatory ducts empty into
● Urethra: The urethra is the tube that carries urine from the bladder to
outside of the body. In males, it has the additional function of ejaculating
semen when the man reaches orgasm. When the penis is erect during
sex, the flow of urine is blocked from the urethra, allowing only semen to
be ejaculated at orgasm.
● Seminal vesicles: The seminal vesicles are sac-like pouches that attach
to the vas deferens near the base of the bladder. The seminal vesicles
produce a sugar-rich fluid (fructose) that provides sperm with a source of
energy to help them move. The fluid of the seminal vesicles makes up
most of the volume of a man's ejaculatory fluid, or ejaculate.
● Prostate gland: The prostate gland is a walnut-sized structure that is
located below the urinary bladder in front of the rectum. The prostate
gland contributes additional fluid to the ejaculate. Prostate fluids also
help to nourish the sperm. The urethra, which carries the ejaculate to be
expelled during orgasm, runs through the center of the prostate gland.
● Bulbourethral glands: Also called Cowper's glands, these are pea-sized
structures located on the sides of the urethra just below the prostate
gland. These glands produce a clear, slippery fluid that empties directly
into the urethra. This fluid serves to lubricate the urethra and to
neutralize any acidity that may be present due to residual drops of urine
in the urethra.
● Penis: This is the male organ used in sexual intercourse. It has three
parts: the root, which attaches to the wall of the abdomen; the body, or
shaft; and the glans, which is the cone-shaped part at the end of the
penis. The opening of the urethra, the tube that transports semen and
urine, is at the tip of the penis. Semen, which contains sperm
(reproductive cells), is expelled (ejaculated) through the end of the penis
when the man reaches sexual climax (orgasm). When the penis is erect,
the flow of urine is blocked from the urethra, allowing only semen to be
ejaculated at orgasm.
A sperm has three main parts:
1. The head of the sperm contains the nucleus. The nucleus holds the
DNA of the cell. The head also contains enzymes that help the sperm
break through the cell membrane of an egg.
2 . The midpiece of the sperm is packed with mitochondria. Mitochondria
are organelles in cells that produce energy. Sperm use the energy in the
midpiece to move.
3. The tail of the sperm moves like a
propeller, around and around. This tail is a
long flagella that pushes the sperm
forward. A sperm can travel about 30
inches per hour.
Functions of the spermatozoon:
The main function of the spermatozoon is
to carry the paternal genetic and to
activate the ovum.
● In humans, spermatogenesis takes 65–75 days. It begins with the spermatogonia,
which contain the diploid (2n) number of chromosomes .
● Primary spermatocytes, like spermatogonia, are diploid (2n); that is, they have 46
chromosomes. Shortly after it forms, each primary spermatocyte replicates its DNA and
then meiosis begins .
In meiosis I, homologous pairs of chromosomes line up at the metaphase plate, and
crossing-over occurs. The two cells formed by meiosis I are called secondary
● Each secondary spermatocyte has 23 chromosomes, the haploid number
(n). Each chromosome within a secondary spermatocyte, is made up of
two chromatids. No replication of DNA occurs in the secondary
● In meiosis II, the chromosomes line up in single ﬁle along the metaphase
plate, and the two chromatids of each chromosome separate. The four
haploid cells resulting from meiosis II are called spermatids
● A single primary spermatocyte therefore produces four spermatids via two
rounds of cell division (meiosis I and meiosis II). . No cell division occurs in
spermiogenesis; each spermatid becomes a single sperm cell.
● Spermatogenesis is controlled by hormonal secretions from hypothalamus and
pituitary gland . The hypothalamus release gonadotropin–releasing hormone
(GnRH) which control the release of the anterior pituitary gonadotropin, follicle –
stimulating hormone (FSH) and luteinizing hormone (LH) .
● FSH stimulates spermatogenesis by stimulating the sertoli cells to complete the
development of sperms from spermatids . The sertoli cells are elongated cells found
in the seminiferous tubules of the testis and they nourish the spermatids.
● LH stimulates leydig cells to release testosterone which causes the growth and
development of germinal epithelial to form sperms .
● Inhibin hormone is produced by the sertoli cells and serves to control the
spermatogenesis at normal rate .
Causes of Infertility in Men
The most frequent cause of infertility in males is low sperm count and/or a
large proportion of abnormal sperm, which can be due to environmental
It appears that a sedentary lifestyle coupled with smoking and alcohol
consumption is most often the cause of male infertility. when males spend
most of the day driving or sitting in front of a computer or TV, the testes’
temperature remains too high for adequate sperm prodution.
Female Reproductive System
● The female reproductive system is
immature at birth and develops to maturity
at puberty to be able to produce gametes,
and to carry a fetus to full term
● Main organs:
1- Vagina. 4 - Fallopian tube.
2 - Cervix. 5- Ovaries.
3 - Uterus.
● it is a fibro-muscular tube, about 10 cm long that extends from the cervix
of the uterus to outside.
● Vagina is located between the rectum and the urinary bladder.
● The vigina serves as a passageway for menstual flow and is the birth canal
● The cervix is the neck of the uterus, the
lower, narrow portion where it joins with
the upper part of the vagina.
● It is cylindrical or conical in shape and
protrudes through the upper anterior
● Approximately half its length is visible, the
remainder lies above the vagina beyond
● The uterus is a muscular organ that receives the fertilized oocyte and
provide an appropriate environment for developing fetus.
● The uterus incubates the embryo.
● The main part of the uterus (which sites in the pelvic cavity) is called the
body of the uterus, while the rounded part above the entrance of the
fallopian tubes is the fundus.
● The thick wall and lining of the uterus is composed of 3 layers:
Endometrium, myometrium and perimetrium.
● The Fallopian tubes are two tubes leading from the ovaries into the uterus.
● On maturity of an ovum, the follicle and the ovary's wall rupture, allowing the
ovum to escape and enter the Fallopian tube.
● There it travels toward the uterus, pushed along by movements of cilia on the
inner lining of the tubes. - Its surface is lined by a serosa and subjacent
● If the ovum is fertilized while in the Fallopian tube, then it normally implants
in the endometrium when it reaches the uterus, which signals the beginning
● The two ovaries are the primary female reproductive organs or gonads.
● Ovaries are small, almond-shaped organs located near lateral walls of
● The ovaries are held in place by various ligaments which attached them to
the uterus and the pelvis.
● The ovary contains ovarian follicles, in which eggs develop.
● Once a follicle is mature, it ruptures and the egg is ejected from the ovary
into the fallopian tubes./ This is called (ovulation)
Function of ovary
1 - Production of female gametes (oocytes).
2 - Secretion of female sex hormones (estrogen , progestin)
The functional units of the ovary are :
1 - Primordial follicles:
● very prevalent ; located in the periphery of the cortex.
● a single layer of squamous follicular cells surround the oocyte.
2 - Growing follicles :
● develop into secondary follicles.
3 - Mature follicles:
● Follicle reaches maximum size before
*All other female reproductive organs help
to transport and provide nutrients to the egg
or developing fetus.
Components of the Ovary
● Surface: The surface layer of the ovary is
formed by simple cuboidal epithelium, known
as germinal epithelium.
● Cortex: The cortex (outer part) of the ovary is
largely comprised of a connective tissue
stroma. It supports thousands of follicles. Each
primordial follicle contains an oocyte
surrounded by a single layer of follicular cells.
● Medulla: The medulla (inner part) is
composed of supporting stroma and contains
a rich neurovascular network which enters the
hilum of ovary from the mesovarium.
The ovum ( the egg cell ) is the female reproductive cell in the female reproductive system ,
It is large in size ( as sesame seed size ) due the the storage of the nutrient materials .
The ovum is not capable of active movement , and it is much larger than the sperms cells ,
when the ovum joins with the sperms during the fertilization , and a diploid cell ( the zygote )
is formed , and the embryo is formed , which gradually grows into a new organism .
The ovum is a spherical cell and not mobile ( static ) , It is one of the largest cells in the
human body , it is visible to the naked eye without the aid of a microscope or other
magnification device , and it is approximately 0.12 mm in diameter .
The ovum consists of the nucleus , the
cytoplasm and the cellular membrane (
that surrounds the cell from outside ) ,
The nucleus contains one half of the
genetic materials ( the chromosomes ) ,
and the cytoplasm stores the food and
the nutrients .
The function of the ovum
The function of the ovum is to carry the set of chromosomes contributed by the female and It
creates the right environment to enable the fertilization by the sperm .
The ova provide the nutrients for the growing embryo until it sinks into the uterus and the placenta
takes over .
the process where the ova or female gametes are produced (“the
beginning of an egg”). it occurs in the outermost layers of the ovaries.
As with sperm production, oogenesis starts with a germ cell, called an
oogonium (plural: oogonia), but this cell undergoes mitosis to increase
in number, eventually resulting in up to one to two million cells in the
1. The cell starting meiosis is called a primary oocyte. This cell
will begin the first meiotic division, but be arrested in its
progress in the first prophase stage.
✓ At the time of birth, all future eggs are in the prophase
2. At adolescence, anterior pituitary hormones cause the
development of a number of follicles in an ovary. This
results in the primary oocyte finishing the first meiotic
division. The cell divides unequally, with most of the cellular
material and organelles going to one cell, called a secondary
oocyte, and only one set of chromosomes and a small amount
of cytoplasm going to the other cell. This second cell is called a
polar body and usually dies.
3. A secondary meiotic arrest occurs, this time at the metaphase
4. At ovulation, this secondary oocyte will be released
and travel toward the uterus through the oviduct.
5. If the secondary oocyte is fertilized, the cell continues
through the meiosis II, completing meiosis, producing
a second polar body and a fertilized egg containing all
46 chromosomes of a human being, half of them
coming from the sperm.
Reproductive Hormones in female
● The hypothalamus, pituitary, and ovaries interact to regulate female reproduction
● Hypothalamus releases Gonadotropin Releasing Hormone (GRH)which binds with receptors in Anterior
● Anterior Pituitary releases Follicle Stimulating Hormone (FSH)and Luteinizing Hormone(LH)pass in
blood to the site of action
● FSH acts on receptors in ovaries to stimulate development of the egg follicles
● LH causes rupture of egg follicles.
● Rupture of egg triggers production of estrogensand progesteronefrom remaining tissues of follicle, corpus
● These hormones travel in blood to the brain
● Hypothalamus senses levels, then may decrease release of GRH (negative feedback mechanism).
MENSTRUAL (uterine) CYCLE
The events of the uterine, or menstrual, cycle are the cyclic changes that the
endometrium, or mucosa of the uterus, goes through month after month as it
responds to changes in the levels of ovarian hormones in the blood.
The cyclic production of estrogens and progesterone by the ovaries is, in turn,
regulated by the anterior pituitary gonadotropic hormones, FSH and LH.
Ovulation typically occurs midway in the cycles, on or about day 14.
• Reflects hormonal changes during ovarian cycle
• Averages 28 days
• Consists of three phases
1) Menstrual phase (decreased oestrogen & progesterone) 1-5 days
• Uterine lining is shed. 5-7 days
2) Proliferative phase (oestrogen) 6 -14 days
• Endometrium renewed in preparation for possible pregnancy
3) Secretory or progestational phase (progesterone). 15- 28 days
• Coincides with luteal phase. Endometrium develops
1) Menstrual phase
– Characterized by discharge of blood and endometrial debris from vagina
– First day of menstruation is considered start of new cycle
– Coincides with end of ovarian luteal phase and onset of follicular phase
– Triggered by decreased oestrogen and progesterone:
– hormones decrease when CL degenerates
– Release of uterine prostaglandin
· Causes vasoconstriction of endometrial vessels
– Disrupts blood supply
– Causes death of endometrium
· Stimulates mild rhythmic contractions of uterine myometrium
– Helps expel the menstrual flow
2) Proliferative phase:
Begins concurrent with last portion of ovarian follicular phase. Uterus prepares for
– Endometrium starts to repair itself and proliferate under influence of
oestrogen from newly-growing follicles
– Oestrogen-dominant proliferative phase lasts from end of menstruation to
– Peak oestrogen levels trigger LH surge responsible for ovulation
3) Secretory phase: Endometrium is prepared for implantation.
– Blood supply increased
– Glands enlarge and secrete glycogen-rich fluids
– Secretory phase conditions promoted by progesterone
– Uterus enters this phase after ovulation when new corpus luteum is formed
– Corpus luteum secretes large amounts of progesterone and oestrogen
● Progesterone converts endometrium to highly vascularized, glycogen-filled
– Endometrial glands actively secrete glycogen
– If fertilization and implantation do not occur
● Corpus luteum degenerates
● New follicular phase and menstrual phase begin again
Hormonal control of the cycle
Gonadotropins (FSH and LH)
Oestrogen and progesterone
● FSH: follicle stimulating hormone growth and development of follicles
● LH: luteinising hormone causes ovulation, development of corpus luteum
● Inhibin: decreases FSH, not LH
– Oestrogen secreted first from the follicle, then from the corpus luteum
– Progesterone secreted from the corpus luteum
– LH and FSH secreted from the anterior pituitary
– Oestrogen and progesterone inhibit LH and FSH secretion
Hormonal control of the cycle
· Stimulate oogenesis and follicle
· Promote proliferative-phase
· Induce expression of uterine
· Induce expression of granulosa
cell LH receptors
· Secondary sexual characteristics
· Breast growth during pregnancy
· Promotes secretory-phase uterine
· Suppresses uterine contraction
· Promotes growth of glandular
breast tissue but suppresses milk
A.Fluctuation of gonadotropin levels:
Fluctuating levels of pituitary
gonadotropins (FSH and LH) in the blood
regulate the events of the ovarian cycle.
(b) Ovarian cycle: Structural changes in
the ovarian follicles during the ovarian
cycle are correlated with (d) changes in
the endometrium of the uterus during the
Hormonal interactions of the female cycles
(c) Fluctuation of ovarian hormone
Fluctuating levels of ovarian
hormones(estrogens and progesterone)
cause the endometrial changes of the
(d) The three phases of the uterine
• Menstrual: Shedding of the functional
layer of the endometrium.
• Proliferative: Rebuilding of the
layer of the endometrium.
• Secretory: Begins immediately after
ovulation. Enrichment of the blood
and glandular secretion of nutrients
prepare the endometrium to receive an
● Fertilization is the fusion of sperm and egg
● Mucus becomes sticky after ovulation and this blocks sperm.
● Thus, fertilization is most likely on the day of ovulation or a day or so preceding
● Successful penetration of the egg by a sperm is dependent on many sperm surrounding
● The ovum completes the second meiotic division after sperm entry
● Conception: Fertilization and implantation
● After about 3-5 days after fertilization the embryo implants in the endometrium
● Membranes that develop around the embryo secrete hCG, human chorionic gonadotrophin.
● After ~ 3 months, uterine tissues begin to form the placenta, the corpus luteum degrades
and the placenta takes over nourishment of the embryo
CAUSES OF INFERTILITY IN WOMEN
The most common causes of female infertility include problems with ovulation,
damage to fallopian tubes or uterus, or problems with the cervix. Age can
contribute to infertility because as a woman ages, her fertility naturally tends to
Ovulation problems may be caused by one
or more of the following:
● A hormone imbalance
● A tumor or cyst
● Eating disorders such as anorexia or bulimia
● Alcohol or drug use
● Thyroid gland problems
● Excess weight
● Intense exercise that causes a significant loss of body fat
● Extremely brief menstrual cycles
Damage to the fallopian tubes or uterus can
be caused by one or more of the following:
● Pelvic inflammatory disease
● A previous infection
● Polyps in the uterus
● Endometriosis or fibroids
● Scar tissue or adhesions
● Chronic medical illness
● A previous ectopic (tubal) pregnancy
● A birth defect
● DES syndrome (The medication DES, given to women to prevent
miscarriage or premature birth can result in fertility problems for their
In Vitro Fertilization (IVF)
● In-vitro fertilization means fertilization outside of female body. It is also known as test tube baby
technique. It is the most effective type of assisted reproductive technology
● It is used when a woman’s fallopian tubes are blocked or when a man produces too few sperms.
● In the IVF procedure, a small incision is made near the umbilicus of female under general anaesthetic
and secondary oocytes are sucked by a hollow needle.
● Sperms are collected from male partner and washed in a culture to remove seminal fluid.
● About 100,000 sperms are added to each sperm about 6 hours after collection of eggs. This is done in
a glass dish.
● The fertilized eggs are grown for about 2 days, after which they are at 2 to 8 cell stage.
● After examination under a microscope, the embryo are transferred through cervix into the uterus using
a fine plastic tube i.e., embryo transfer.
● Essentials of Human Anatomy Physiology - Marieb, Elaine N. chapter 16 page 551
● Principles of Anatomy and Physiology 13th ed - G. Tortora, B. Derrickson (Wiley,