Chapter 27
The Reproductive System
1019
27
reproductive organs are quite different, their common purpose
is to produce offspring.
Te male’s reproductive role is to manufacture male gametes
called
sperm
and deliver them to the female reproductive tract,
where fertilization can occur. Te complementary role of the fe-
male is to produce female gametes, called
ova
or
eggs
. As a result
of appropriately timed intercourse, a sperm and an egg may fuse
to form a fertilized egg, or
zygote
. Te zygote is the first cell of a
new individual, from which all body cells will arise.
Te male and female reproductive systems are equal part-
ners in events leading up to fertilization, but once fertilization
has occurred, the female partner’s uterus provides the protec-
tive environment where the embryo develops until birth. Sex
hormones—androgens in males and estrogens and progester-
one in females—play vital roles both in the development and
function of the reproductive organs and in sexual behavior and
drives. Tese hormones also influence the growth and develop-
ment of many other organs and tissues of the body.
Anatomy of the Male
Reproductive System
Describe the structure and function of the testes, and
explain the importance of their location in the scrotum.
Te sperm-producing
testes
(tes
9
tez; “witnesses”), or
male go-
nads
, lie within the
scrotum
. From the testes, the sperm are de-
livered to the body exterior through a system of ducts including
(in order) the
epididymis
, the
ductus deferens
, the
ejaculatory
duct
, and finally the
urethra
, which opens to the outside at the
tip of the
penis
. Te accessory sex glands, which empty their
secretions into the ducts during ejaculation, are the
seminal
glands, prostate
, and
bulbo-urethral glands
. ±ake a moment to
trace the duct system in
Figure 27.1
, and identify the testis and
accessory glands before continuing.
The Scrotum
Te
scrotum
(skro
9
tum; “pouch”) is a sac of skin and superfi-
cial fascia that hangs outside the abdominopelvic cavity at the
root of the penis (Figure 27.1 and
Figure 27.2
). It is covered
with sparse hairs, and contains paired oval testes. A midline
septum
divides the scrotum, providing a compartment for
each testis.
Tis seems a rather vulnerable location for a man’s testes,
which contain his entire ability to father offspring. However,
because viable sperm cannot be produced in abundance at core
body temperature (37°C), the superficial location of the scro-
tum, which provides a temperature about 3°C lower, is an es-
sential adaptation.
Peritoneum
Seminal gland (vesicle)
Ampulla of
ductus deferens
Ejaculatory duct
Rectum
Prostate
Bulbo-urethral gland
Anus
Bulb of penis
Epididymis
Ureter
Urinary bladder
Prostatic urethra
Pubis
Intermediate part of
the urethra
Urogenital diaphragm
Corpus cavernosum
Corpus spongiosum
Glans penis
Prepuce (foreskin)
External urethral
orifice
Spongy urethra
Testis
Scrotum
Ductus (vas) deferens
Figure 27.1
Reproductive organs of the male, sagittal view.
A portion of the pubis of
the hip bone has been left to show the relationship of the ductus deferens to the bony pelvis.
(For related images, see
A Brief Atlas of the Human Body
, Figures 72 and 73.)
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