Composed of the same material that ovaries
are formed from, a man’s testicles originally develop in his
abdomen. About two months before his birth, though, the two
testes descend from the abdomen into the scrotum, which acts
as a support sac to the testicles. The main function of
testicles is two-fold: they are responsible for producing
sperm as well as the hormone testosterone. The testicles are
made up of seminiferous tubules (hundreds of tiny tubes),
Leydig cells (which is where testosterone is produced), and
Sertoli cells (which are responsible for nurturing immature
Because the testicles need to remain about 1°C cooler than
normal body temperature, the scrotum helps to regulate the
temperature of the testes. When exposed to cold air, the
scrotum contracts to keep the testes warm but hangs lower
when it is hot outside.
at the top of the testes, the epididymus is a set of tightly
coiled tubes. How tightly coiled? Well, if you stretched it
out, the epididymus would reach 20 feet long. The epididymus
acts as a temporary storing place for sperm as they continue
to mature. It is within these tubes that sperm gain the
ability to move.
long tube extends from the epididymus in the testicle, up,
over the bladder and finally ending at the seminal vesicles.
The vas deferens acts as both a passageway for the sperm as
they exit the body and as another storing place as the sperm
wait to be ejaculated.
These two pouch-like sacs are found behind
the bladder. The seminal vesicles add an alkaline fluid that
makes up 30% of the total semen volume. This secretion helps
give the sperm energy, thereby giving their motility a
This gland sits just below the bladder and
contributes about 60% of the total semen volume. This
alkaline secretion is similar to the fluid produced in the
seminal vesicles and is necessary to the sperms’ survival by
helping neutralize the naturally occurring acids in the
urethra and the vagina.
Positioned just below the prostate, these are
two small glands that produce about 5% of the alkaline
secretions that make up semen.
These are two short ducts that connect the
prostate gland to the urethra. The joining of the two vas
deferens makes up the ejaculatory ducts.
Used as the final passageway for both semen
and urine, this tube starts at the bladder, goes through the
prostate and extends to the tip of the penis. When a man
climaxes, the prostate closes off the bladder to prevent any
urine from joining the semen.
The method of delivery for sperm, this organ
is made up of veins, arteries and spongy tissue. When a man
becomes sexually aroused, the arteries dilate allowing the
tissue to become engorged with blood. This causes the penis
to stiffen and become erect.
Gonadotropin Releasing Hormone (GnRH):
Originating in the hypothalamus in the brain, GnRH is
responsible for signaling the pituitary gland to start
production of follicle stimulating hormone (FSH) and
lutenizing hormone (LH).
This hormone is
responsible for stimulating and maintaining sperm
hormone is responsible for getting the production of
in the Leydig cells in the testes, this hormone helps with
sperm production but it is mainly responsible for male
maturation (the deepening of the voice, sex drive, growth
and development of the sex organs).
Making It All Work
At birth, males have simple round cells contained within
their seminiferous tubules. This is the most primitive form
of sperm. During puberty, stimulation by testosterone and
other hormones cause the cells to divide, thereby beginning
the maturation process of sperm. The sperm cells will divide
and mature until they begin to resemble tadpoles, with an
oval head and long, thin tail. Contained within the sperm
head is all of the genetic information that a man
contributes to his child. The tail is used to propel the
sperm along its journey.
Once the sperm has developed its head and tail, it is
shuttled along to the epididymus. Here it will enjoy a
three-week stay by the end of which it will have gained the
ability to move. Next, the sperm move through the vas
deferens to the seminal vesicles where they stay until they
are ejaculated. All along this trip, the sperm will be
provided with fructose, a type of sugar, to give it energy
as it travels along.
During ejaculation, fluid from the prostate, seminal
vesicles, and Cowper’s gland combine with the sperm to make
semen. This will be expelled from the body during orgasm.
For fertilization of the female egg to occur, it is
necessary to ejaculate inside the vagina.
Anywhere from 250 million to 1 billion sperm are produced
and ejaculated at one time in a healthy male. However, only
about 200 of these will actually make it up through the
vagina, cervix and uterus and into the correct fallopian
tube. From this drastically reduced group, only one sperm
will actually be able to fuse together with the egg to
create a child. In total, it takes a few days for sperm to
make the trip through the female reproductive system to the