Male Reproductive System
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
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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
Male Reproductive system
• The scrotum
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The testes
The spermatic cord
The seminal vesicles
The ejaculatory ducts
The prostate glands
The penis
The scrotum
Functions:
The scrotum forms a pouch in which the testes are
suspended outside the body. It lies below the
symphysis pubis and between the upper –parts of the
thighs behind the penis.
Structure
• It is formed of pigmented skin and has
two compartments ,one for each testis.
The testes
Function:
• The testes are the male gonads and produce
spermatozoa and the hormone testosterone.
• Testosterone is responsible for the development of
secondary sex characteristics.
• Together with FSH,it also promotes production of
sperm.
Position
• The testes are situated in the scrotum.
Design
Plan
• In
order to achieve
their proper function they
must be kept below body temperature, and that
is why they are situated outside the body.
Structures
• Each testis is 4.5 cm long,2.5 cm wide and 3
cm thick.
The seminiferous tubules
• These are where spermatogenesis or
production of sperm takes place.
• Between the tubules are interstitial cells that
secrete testosterone.
• The tubules join to form a system of channels
that leads to the epididymis
Epididymis
• This is a comma shaped coiled tube that lies
on the superior surface and travels down the
posterior aspect to the lower pole of the testis.
The seminal vesicles
Function:
• production of a viscous secretion to keep the
sperm alive and motile.
Position
• The seminal vesicles are two pouches situated
posterior to the bladder.
Structure
• The seminal vesicles are 5 cm ,long and are
pyramid shaped.
The ejaculatory ducts
• These small muscular ducts carry the
spermatozoa and the seminal fluid to the
urethra.
The prostate glands
Function:
• The prostate gland produces a thin lubricating
fluid that enters the urethra through ducts.
The penis
Functions
• It carries the urethra, which is a passage for
both urine and semen.
• During sexual excitement it stiffens ( an
erection ) in order to able to penetrate the
vagina and deposit the semen near to the
women’s cervix.
• consists of three columns of erectile tissue that
are wrapped in connective tissue and covered
with skin. The two dorsal columns are the
corpora cavernosa. The single, midline ventral
column surrounds the urethra and is called the
corpus spongiosum.
penis
• 3 parts: a root, body (shaft), and glans penis.
• The root of the penis attaches it to the pubic arch
• the body is the visible, pendant portion.
• The corpus spongiosum expands at the distal end to form the
glans penis.
• The urethra, which extends throughout the length of the
corpus spongiosum, opens through the external urethral orifice
at the tip of the glans penis. A loose fold of skin, called the
prepuce, or foreskin, covers the glans penis.
Hormones
Follicle-stimulating hormone (FSH) stimulates
spermatogenesis
• Interstitial Cell Stimulating Hormone (ICSH)
stimulates the production of testosterone
• testosterone stimulates the development of
male secondary sex characteristics &
spermatogenesis.
Formation of spermatozoa
 Production of sperm begins at puberty and
continues throughout adult life.
 Spermatogenesis takes place in the
seminiferous tubules under the influence of
FSH and testosterone.
 The mature sperm is stored in the epididymis
and the deferent duct until ejaculation
 At each ejaculation , 2-4 ml of semen are
deposited in the vagina.
 The seminal fluids contain about 100 million
sperms per ml.
 The individual spermatozoan has a head, a
body and a long motile tail that lashes to
propel the sperm along .
• The tip of the head is covered by an acrosome
; this contains enzyme to dissolve the covering
of the ovum inorder to penetrate it.