Male reproductive system by Pandian M, tutor, Dept of Physiology, DYPMCKOP,MH

PANDIAN M
DEPT OF PHYSIOLOGY
DYPMCKOP

SLO
• Male reproductive functions
• The male reproductive tract
• Sagittal segments of testes and epididymis
• Adolescence
• General Physical Changes
• Stages of spermatogenesis
• Structure of the human spermatozoon.
• Pathway for the passage of sperms
• SEMEN
• Composition & function
• Capacitation
• Factors affecting spermatogenesis
• Hormones necessary for spermatogenesis
• Functions of testosterone
• Disorders of sexual development / applied

Male reproductive functions can be divided into three
major subdivisions:
(1) spermatogenesis, which means the formation of
sperm;
(2) Performance of the male sexual act; and
(3) Regulation of male reproductive functions by the
various hormones.
-Guyton & hall

THE MALE REPRODUCTIVE TRACT
It consists of glands with their ducts & supporting
structure.
I. The glands include:
1. A pair of testes
2. A pair of seminal vesicles
3. A pair of bulbourethral (cowper’s) glands and
4. One prostate gland

II. Ducts of testes:
1. A pair of epididymis
2. A pair of vas deferens
3. A pair of ejaculatory ducts, and
4. One urethra.
III. Supporting structures are divided into:
1. Internal: a pair of spermatic cords &
2. External: scrotum & penis.

testes are located in
the dangling scrotum is to
maintain the temperature

ADOLESCENCE
• Puberty
• Burst of hormones activate maturation of the gonads:
testes
• Begins: 9 – 14 yrs of age
• Abnormally early = precocious puberty
• Delayed = eunuchoidism

GENERAL PHYSICAL CHANGES
•Enlargement of the external and internal
genitalia
•Voice changes
•Hair growth
•Mental changes
•Changes in body conformation and skin
•Sebaceous gland secretions thicken/increase
 acne

TESTES
• Each testis is an oval structure about 5 cm long and 3 cm in diameter
• Covered by: tunica albuginea
• Located in the dangling scrotum
• There are about 250 lobules in each testis.
• Each contains 1 to 4 -seminiferous tubules that converge to form a single
straight tubule, which leads into the rete testis.
• Short efferent ducts exit the testes.
• Interstitial cells (cells of leydig), which produce male sex hormones, are
located between the seminiferous tubules within a lobule.

STAGES OF
SPERMATOGENESIS
Spermatogenesis occurs in four stages:
1. Stage of proliferation
2. Stage of growth
3. Stage of maturation
4. Stage of transformation.

1. STAGE OF PROLIFERATION
• Each spermatogonium contains diploid number (23 pairs) of
chromosomes.
• The 23 pairs include 22 pairs of autosomal chromosomes and one
pair of sex chromosomes.
• During this state spermatogonia divide by mitosis, without any
change in chromosomal number.
• The last generation enters the stage of growth as primary
spermatocyte.

2. Stage of growth
• In this stage, the primary spermatocyte grows into a large cell.
• Apart from growth, there is no other change in spermatocyte
during this stage.
3. Stage of Maturation
After reaching the full size, each primary spermatocyte quickly
undergoes meiotic or maturation division,
which occurs in two phases: first phase and second phase

FIRST PHASE:
•Each primary spermatocyte divides into two
secondary spermatocytes.
•The significance of the first meiotic division is each
secondary spermatocyte receives only the haploid or
half the number of chromosomes.
•23 chromosomes include 22 autosomes and a x or a y
chromosome.

SECOND PHASE:
• During this phase, each secondary spermatocyte undergoes
second meiotic division,
• Resulting in two smaller cells called spermatids.
• Each spermatid has haploid number of chromosomes.
The entire period of spermatogenesis, from spermatogonia to
spermatozoa, takes about 74 days.

4. STAGE OF TRANSFORMATION
•There is no further division.
•Spermatids are transformed into matured
spermatozoa (sperms),
•By means of spermeogenesis and released by
spermination.

STAGES IN THE DEVELOPMENT OF SPERM
FROM SPERMATOGONIA.

STRUCTURE OF THE HUMAN
SPERMATOZOON.

PATHWAY FOR THE
PASSAGE OF SPERMS
6-meter-long
18 to 24 hours, they
develop the
capability of motility

SEMEN
SPERMS 10% SEMINAL PLASMA 90%

“CAPACITATION” OF SPERMATOZOA IS
REQUIRED FOR FERTILIZATION OF THE OVUM
• When they are first expelled in the semen, they are unable to
fertilize the ovum.
• However, on coming in contact with the fluids of the female
genital tract, multiple changes occurs.
• That activate the sperm for the final processes of fertilization.
• These collective changes are called capacitation of the
spermatozoa, which normally requires from 1 to 10 hours.

FUNCTIONS OF SEMINAL FLUID
• Nutrition to sperms:-
Fructose and other nutritive substances in seminal fluid
are utilized by sperms after being ejaculated into the female
genital tract.
• Clotting of semen:-
Immediately after ejaculation, semen clots because of the
conversion of fibrinogen from seminal fluid into fibrin.

• Fertilization:-
Prostaglandin of seminal fluid enhances fertilization of
ovum by:
1. Increasing the receptive capacity of cervical mucosa for
sperms
2. Initiating reverse peristaltic movement of uterus and
fallopian tubes. This in turn, increases the rate of transport of
sperms in female genital tract during coitus (oxytocin is also
responsible for this process).

PROSTATE GLAND
• Human prostate gland weighs about 40 g.
• It consists of 20 to 30 separate glands, which open separately
into the urethra.
• These glands are tubuloalveolar in nature.
• Prostate fluid is a thin, milky and alkaline fluid.
• It forms 30% of total semen.
Functions of prostatic fluid:-
1. Maintenance of sperm motility, 2. Clotting of semen& 3.Lysis of
coagulum

CROSS SECTION OF A SEMINIFEROUS TUBULE.

FACTORS AFFECTING
SPERMATOGENESIS
SPERMATOGENESIS IS INFLUENCED
BY:
1. SERTOLI CELLS
2. HORMONES
3. OTHER FACTORS.

1. Role of sertoli cell in spermatogenesis:
Sertoli cells influence spermatogenesis by:
I. Supporting and nourishing the germ cells
II. Providing hormonal substances necessary for
spermatogenesis
III. Secreting androgen-binding protein (ABP), which
is essential for testosterone activity, particularly on
spermatogenesis
IV. Releasing sperms into the lumen of seminiferous
tubules (spermination).

2. Role of hormones in spermatogenesis
Spermatogenesis is influenced by many hormones,
(Which act either directly or indirectly)
Hormones necessary for spermatogenesis are:
I. Follicle-stimulating hormone (FSH)
II. Testosterone
III. Luteinizing hormone (LH)
V. Growth hormone (GH)
VI. Inhibin
VII. Activin.

HORMONES NECESSARY FOR
SPERMATOGENESIS

3. ROLE OF OTHER FACTORS IN
SPERMATOGENESIS
I. Increase in body temperature- prevents spermatogenesis.
• Normally, the temperature in scrotum is about 2°c less than the
body temperature.
• It is very common in cryptorchidism (undescended testes).
II. Diseases: infectious diseases such as mumps cause
degeneration of seminiferous tubules and stoppage of
spermatogenesis.

Summary of hormonal
control of male
reproductive function.

PENILE ERECTION—ROLE OF THE
PARASYMPATHETIC NERVES.
• The degree of erection is proportional to the degree of stimulation,
whether psychic or physical.
• Erection is caused by parasympathetic impulses from the sacral
portion of the spinal cord pelvic nerves to the penis.
• Release nitric oxide and/or vasoactive intestinal peptide in addition to
acetylcholine
• Nitric oxide - activates the enzyme guanylyl cyclase, causing increased
formation of cyclic guanosine monophosphate (GMP). Relaxes the
arteries in penis.

EMISSION AND EJACULATION ARE FUNCTIONS OF
THE
SYMPATHETIC NERVES
• When the sexual stimulus becomes extremely intense the reflex
centers of the spinal cord,
• Begin to emit sympathetic impulses that leave the cord at T12
to L2 and
• Pass to the genital organs through the hypogastric and pelvic
sympathetic nerve plexuses to initiate emission, the forerunner
of ejaculation.

FUNCTIONS OF TESTOSTERONE
1. Sex differentiation in fetus
2. Development of accessory sex organs
3. Descent of the testes.

DISORDERS OF SEXUAL
DEVELOPMENT

Abnormalities of sexual development occur due to:
• Defect in sex chromosomes leading to genetic
abnormalities.
• Hormonal abnormalities leading to defect in gonadal
and genital differentiation
•There are :
1.Cryptorchidism and
2.Klinefelter syndrome(xxy)
3.Superfemale (XXX)

• Chromosomal abnormalities
Trisomy:-
1. Klinefelter syndrome(xxy)
2. Superfemale (XXX)
Monosomy
1. Turner’s syndrome. (44 + yo)

KLINEFELTER’S SYNDROME
• Individual with XXY pattern of chromosomes
• (Klinefelter syndrome) is an abnormal male due to presence
of Y chromosome.
• It is the most common sex chromosome Disorder, has an
incidence of 1 in 500 males.

Tall stature,
Famine stigmata, bilateral
gynaecomastia
And small size external
genitalia

KLINEFELTER SYNDROME
• Disorder of gonadal development
• Non – dysfunction in male germ cells is thought to account for
50% of the cases
• By screening for sex chromatin positive – phenotypic males,
the syndrome has been found in 1 in 400 or 500 new born’s
• Dominants chromosomal feature in almost all patients is at
least an XXY chromosome pattern

• Classic form of K syndrome is characterized by small, firm
testes with hyalinization of seminiferous tubules -
• Azoospermia
• Gynecomastia
• Elevated serum and urinary gonadotropin
• Mental retardation
• Impairment of social and mental function.

Other’s causes:
• Mumps orchitis
• Cryptorchidism (failure of testes to descend into scrotum)
• Testicular damage from radiation or chemotherapy.
Treatment:
• Steroid replacement therapy
• Maintain only secondary sexual characters only normal
growth of public/axillary hair sexual function – no fertility.

WHY DOES ONLY ONE SPERM ENTER
THE OOCYTE?
• CA2++ IONS.
• MULTIPLE CORTICAL GRANULES TO BE
RELEASED BY EXOCYTOSIS FROM THE
OOCYTE INTO THE PERIVITELLINE
SPACE.

REFERENCES
• TEXT BOOK OF MEDICAL PHYSIOLOGY
• GUYTON & HALL
• HUMAN PHYSIOLOGY
• VANDER
• TEXT BOOK OF MEDICAL PHYSIOLOGY
• INDUKURANA
• PRINCIPLES OF ANATOMY AND PHYSIOLOGY
• TOTORA
• NET SOURCE

Male reproductive system by Pandian M, tutor, Dept of Physiology, DYPMCKOP,MH

Male reproductive system by Pandian M, tutor, Dept of Physiology, DYPMCKOP,MH

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Male reproductive system by Pandian M, tutor, Dept of Physiology, DYPMCKOP,MH