1046 Unit 5 Continuity
27 The Reproductive
why this
System matters
In this chapter, you will learn that
The reproductive organs complement each other’s function in reproducing the body
by comparing
Male Female
by exploring by exploring
Part 1 Male Part 2 Male Part 3 Female Part 4 Female
Reproductive Reproductive Reproductive Reproductive
Anatomy Physiology Anatomy Physiology
looking closer at looking closer at looking closer at looking closer at
27.1 Scrotum 27.5 Male sexual 27.8 Ovaries 27.12 Oogenesis
and testes response
27.9 Female 27.13 The ovarian
27.2 Penis 27.6 Spermatogenesis duct system cycle
and asking and asking
27.3 Male duct 27.10 External
system genitalia
27.7 How is male 27.14 How is female
reproductive reproductive
function regulated? function regulated?
27.4 Male 27.11 Mammary
accessory glands glands
using and next examining
and semen
27.15 Female sexual
Endocrine system Ch. 16 using
response
and then asking
Part 5 What are some
common sexually
transmitted infections?
and finally, exploring
< A happy couple.
Developmental Aspects
of the Reproductive System
1046
M27_MARI6971_10_SE_CH27_1046-1093.indd 1046
, Chapter 27 The Reproductive System 10
M
ost organ systems function almost continuously to main- hormones—androgens in males and estrogens and proges
tain the well-being of the individual. The reproductive one in females—play vital roles both in the development
system, however, appears to “slumber” until puberty. function of the reproductive organs and in sexual behavior
The primary sex organs, or gonads (go′nadz; “seeds”), are the drives. These hormones also influence the growth and devel
testes in males and the ovaries in females. The gonads produce ment of many other organs and tissues of the body.
sex cells, or gametes (gam′ēts; “spouses”), and secrete a vari-
ety of steroid hormones commonly called sex hormones. The Part 1
remaining reproductive structures—ducts, glands, and external
genitalia (jen-ĭ-ta′le-ah)—are accessory reproductive organs. Anatomy of The Male
Although male and female reproductive organs are quite differ-
ent, their common purpose is to produce offspring. Reproductive System
The male’s reproductive role is to manufacture male gam- The sperm-producing testes (tes′tez), or male gonads,
etes called sperm and deliver them to the female reproductive within the scrotum. From the testes, the sperm are delive
tract, where fertilization can occur. The complementary role to the body exterior through a system of ducts including
of the female is to produce female gametes, called ova or eggs. order) the epididymis, the ductus deferens, the ejaculatory d
As a result of appropriately timed intercourse, a sperm and and finally the urethra, which opens to the outside at the ti
an egg may fuse to form a fertilized egg, or zygote. The zygote the penis. The accessory sex glands, which empty their se
is the first cell of a new individual, from which all body cells tions into the ducts during ejaculation, are the seminal gla
will arise. prostate, and bulbo-urethral glands. Take a moment to trace
The male and female reproductive systems are equal part- duct system in Figure 27.1, and identify the testis and ac
ners in events leading up to fertilization, but once fertilization sory glands before continuing.
has occurred, the female partner’s uterus provides the protec-
tive environment where the embryo develops until birth. Sex
Ureter
Peritoneum
Urinary bladder
Seminal gland (vesicle)
Prostatic urethra
Ampulla of
ductus deferens Pubis
Ejaculatory duct Intermediate par
the urethra
Rectum
Urogenital diaphra
Prostate
Corpus cavernos
Bulbo-urethral gland
Corpus spongios
Anus
Spongy urethra
Bulb of penis
Ductus (vas) deferens
Epididymis Glans penis
Testis Prepuce (foreski
Scrotum External urethral
orifice
Figure 27.1 Reproductive organs of the male, sagittal view. A portion of the pubis of Practice art labeling
the hip bone has been left to show the relationship of the ductus deferens to the bony pelvis. >Study Area>Chapte
(For related images, see A Brief Atlas of the Human Body, Figures 72 and 73.)
M27_MARI6971_10_SE_CH27_1046-1093.indd 1047
, 1048 Unit 5 Continuity
becomes shorter and heavily wrinkled, decreasing its surface
27.1The testes are enclosed and area and increasing its thickness to reduce heat loss. When it is
protected by the scrotum warm, the scrotal skin is flaccid and loose to increase the sur-
face area for cooling (sweating) and the testes hang lower, away
Learning Objective from the body trunk.
Describe the structure and function of the testes, and These changes in scrotal surface area help maintain a fairly
explain the importance of their location in the scrotum. constant intrascrotal temperature and reflect the activity of two
sets of muscles that respond to ambient temperature. The
The Scrotum dartos muscle (dar′tos; “skinned”), a layer of smooth muscle in
the superficial fascia, wrinkles the scrotal skin. The cremaster
The scrotum (skro′tum; “pouch”) is a sac of skin and superficial
muscles (kre-mas′ter; “a suspender”), bands of skeletal muscle
fascia that hangs outside the abdominopelvic cavity at the root
that arise from the internal oblique muscles of the trunk, elevate
of the penis (Figure 27.1 and Figure 27.2). It is covered with
the testes.
sparse hairs, and contains paired oval testes. A midline septum
divides the scrotum, providing a compartment for each testis.
This seems a rather vulnerable location for a man’s testes, The Testes
which contain his entire ability to father offspring. However, Each plum-sized testis is approximately 4 cm (1.5 inches) long by
because viable sperm cannot be produced in abundance at core 2.5 cm (1 inch) wide and is surrounded by two tunics. The outer
body temperature (37°C), the superficial location of the scro- tunic is the two-layered tunica vaginalis (vaj″ĭ-nal′is), derived
tum, which provides a temperature about 3°C lower, is an essen- from an outpocketing of the peritoneum (Figure 27.2 and
tial adaptation. Figure 27.3a). Deep to this serous layer is the tunica albuginea
Furthermore, the scrotum is affected by temperature (al″bu-jin′e-ah; “white coat”), the fibrous capsule of the testis.
changes. When it is cold, the testes are pulled closer to the pel- Septa extending inward from the tunica albuginea divide the
vic floor and the warmth of the body wall, and the scrotum testis into about 250 wedge-shaped lobules. Each contains one
Urinary bladder
Superficial inguinal ring
(end of inguinal canal) Testicular artery
Spermatic cord
Ductus (vas)
deferens
Penis Autonomic
nerve fibers
Septum of scrotum
Pampiniform
venous plexus
Cremaster muscle Epididymis
27
Tunica vaginalis
External spermatic (from peritoneum)
fascia Tunica albuginea
Superficial fascia of testis
Scrotum containing dartos muscle Internal spermatic
Skin fascia
Figure 27.2 Relationships of the testis to the scrotum and spermatic cord. The scrotum
has been opened and its anterior portion removed.
M27_MARI6971_10_SE_CH27_1046-1093.indd 1048
, Chapter 27 The Reproductive System 10
Spermatic cord
Blood vessels
and nerves
Ductus deferens
Ductus (vas) Epididymis
deferens
Testis
Head of epididymis
Seminiferous
Efferent ductule
tubule
Rete testis
Lobule
Straight tubule Septum
Tunica albuginea
Body of epididymis
Tunica vaginalis
Duct of epididymis Cavity of
tunica vaginalis
Tail of epididymis
(a) (b)
Sperm
Seminiferous
tubule
Areolar
connective
tissue
(c) Interstitial Myoid Spermatogenic Sustentocyte
endocrine cells cells in tubule
cells epithelium
Figure 27.3 Structure of the testis. (a) Partial sagittal section to four tightly coiled seminiferous tubules (sem″ĭ-nif′er
through the testis and epididymis. The anterior aspect is to the right. “sperm-carrying”), the actual “sperm factories” consisting
(For a related image, see A Brief Atlas of the Human Body, Figure a thick stratified epithelium surrounding a central flu
73). (b) External view of a testis from a cadaver; same orientation containing lumen (Figure 27.3a and c). The epithelium cons
as in (a). (c) Seminiferous tubule in cross section (270×). Note the of spheroid spermatogenic (“sperm-forming”) cells embed
spermatogenic (sperm-forming) cells in the tubule epithelium and in substantially larger columnar cells called sustentocytes.
the interstitial endocrine cells in the connective tissue between the
sustentocytes are supporting cells that play several roles
tubules.
sperm formation, as described shortly.
Surrounding each seminiferous tubule are three to five la
View histology slides
of smooth muscle–like myoid cells (Figure 27.3c). By contr
>Study Area>
ing rhythmically, myoid cells may help to squeeze sperm
testicular fluids through the tubules and out of the testes.
M27_MARI6971_10_SE_CH27_1046-1093.indd 1049
27 The Reproductive
why this
System matters
In this chapter, you will learn that
The reproductive organs complement each other’s function in reproducing the body
by comparing
Male Female
by exploring by exploring
Part 1 Male Part 2 Male Part 3 Female Part 4 Female
Reproductive Reproductive Reproductive Reproductive
Anatomy Physiology Anatomy Physiology
looking closer at looking closer at looking closer at looking closer at
27.1 Scrotum 27.5 Male sexual 27.8 Ovaries 27.12 Oogenesis
and testes response
27.9 Female 27.13 The ovarian
27.2 Penis 27.6 Spermatogenesis duct system cycle
and asking and asking
27.3 Male duct 27.10 External
system genitalia
27.7 How is male 27.14 How is female
reproductive reproductive
function regulated? function regulated?
27.4 Male 27.11 Mammary
accessory glands glands
using and next examining
and semen
27.15 Female sexual
Endocrine system Ch. 16 using
response
and then asking
Part 5 What are some
common sexually
transmitted infections?
and finally, exploring
< A happy couple.
Developmental Aspects
of the Reproductive System
1046
M27_MARI6971_10_SE_CH27_1046-1093.indd 1046
, Chapter 27 The Reproductive System 10
M
ost organ systems function almost continuously to main- hormones—androgens in males and estrogens and proges
tain the well-being of the individual. The reproductive one in females—play vital roles both in the development
system, however, appears to “slumber” until puberty. function of the reproductive organs and in sexual behavior
The primary sex organs, or gonads (go′nadz; “seeds”), are the drives. These hormones also influence the growth and devel
testes in males and the ovaries in females. The gonads produce ment of many other organs and tissues of the body.
sex cells, or gametes (gam′ēts; “spouses”), and secrete a vari-
ety of steroid hormones commonly called sex hormones. The Part 1
remaining reproductive structures—ducts, glands, and external
genitalia (jen-ĭ-ta′le-ah)—are accessory reproductive organs. Anatomy of The Male
Although male and female reproductive organs are quite differ-
ent, their common purpose is to produce offspring. Reproductive System
The male’s reproductive role is to manufacture male gam- The sperm-producing testes (tes′tez), or male gonads,
etes called sperm and deliver them to the female reproductive within the scrotum. From the testes, the sperm are delive
tract, where fertilization can occur. The complementary role to the body exterior through a system of ducts including
of the female is to produce female gametes, called ova or eggs. order) the epididymis, the ductus deferens, the ejaculatory d
As a result of appropriately timed intercourse, a sperm and and finally the urethra, which opens to the outside at the ti
an egg may fuse to form a fertilized egg, or zygote. The zygote the penis. The accessory sex glands, which empty their se
is the first cell of a new individual, from which all body cells tions into the ducts during ejaculation, are the seminal gla
will arise. prostate, and bulbo-urethral glands. Take a moment to trace
The male and female reproductive systems are equal part- duct system in Figure 27.1, and identify the testis and ac
ners in events leading up to fertilization, but once fertilization sory glands before continuing.
has occurred, the female partner’s uterus provides the protec-
tive environment where the embryo develops until birth. Sex
Ureter
Peritoneum
Urinary bladder
Seminal gland (vesicle)
Prostatic urethra
Ampulla of
ductus deferens Pubis
Ejaculatory duct Intermediate par
the urethra
Rectum
Urogenital diaphra
Prostate
Corpus cavernos
Bulbo-urethral gland
Corpus spongios
Anus
Spongy urethra
Bulb of penis
Ductus (vas) deferens
Epididymis Glans penis
Testis Prepuce (foreski
Scrotum External urethral
orifice
Figure 27.1 Reproductive organs of the male, sagittal view. A portion of the pubis of Practice art labeling
the hip bone has been left to show the relationship of the ductus deferens to the bony pelvis. >Study Area>Chapte
(For related images, see A Brief Atlas of the Human Body, Figures 72 and 73.)
M27_MARI6971_10_SE_CH27_1046-1093.indd 1047
, 1048 Unit 5 Continuity
becomes shorter and heavily wrinkled, decreasing its surface
27.1The testes are enclosed and area and increasing its thickness to reduce heat loss. When it is
protected by the scrotum warm, the scrotal skin is flaccid and loose to increase the sur-
face area for cooling (sweating) and the testes hang lower, away
Learning Objective from the body trunk.
Describe the structure and function of the testes, and These changes in scrotal surface area help maintain a fairly
explain the importance of their location in the scrotum. constant intrascrotal temperature and reflect the activity of two
sets of muscles that respond to ambient temperature. The
The Scrotum dartos muscle (dar′tos; “skinned”), a layer of smooth muscle in
the superficial fascia, wrinkles the scrotal skin. The cremaster
The scrotum (skro′tum; “pouch”) is a sac of skin and superficial
muscles (kre-mas′ter; “a suspender”), bands of skeletal muscle
fascia that hangs outside the abdominopelvic cavity at the root
that arise from the internal oblique muscles of the trunk, elevate
of the penis (Figure 27.1 and Figure 27.2). It is covered with
the testes.
sparse hairs, and contains paired oval testes. A midline septum
divides the scrotum, providing a compartment for each testis.
This seems a rather vulnerable location for a man’s testes, The Testes
which contain his entire ability to father offspring. However, Each plum-sized testis is approximately 4 cm (1.5 inches) long by
because viable sperm cannot be produced in abundance at core 2.5 cm (1 inch) wide and is surrounded by two tunics. The outer
body temperature (37°C), the superficial location of the scro- tunic is the two-layered tunica vaginalis (vaj″ĭ-nal′is), derived
tum, which provides a temperature about 3°C lower, is an essen- from an outpocketing of the peritoneum (Figure 27.2 and
tial adaptation. Figure 27.3a). Deep to this serous layer is the tunica albuginea
Furthermore, the scrotum is affected by temperature (al″bu-jin′e-ah; “white coat”), the fibrous capsule of the testis.
changes. When it is cold, the testes are pulled closer to the pel- Septa extending inward from the tunica albuginea divide the
vic floor and the warmth of the body wall, and the scrotum testis into about 250 wedge-shaped lobules. Each contains one
Urinary bladder
Superficial inguinal ring
(end of inguinal canal) Testicular artery
Spermatic cord
Ductus (vas)
deferens
Penis Autonomic
nerve fibers
Septum of scrotum
Pampiniform
venous plexus
Cremaster muscle Epididymis
27
Tunica vaginalis
External spermatic (from peritoneum)
fascia Tunica albuginea
Superficial fascia of testis
Scrotum containing dartos muscle Internal spermatic
Skin fascia
Figure 27.2 Relationships of the testis to the scrotum and spermatic cord. The scrotum
has been opened and its anterior portion removed.
M27_MARI6971_10_SE_CH27_1046-1093.indd 1048
, Chapter 27 The Reproductive System 10
Spermatic cord
Blood vessels
and nerves
Ductus deferens
Ductus (vas) Epididymis
deferens
Testis
Head of epididymis
Seminiferous
Efferent ductule
tubule
Rete testis
Lobule
Straight tubule Septum
Tunica albuginea
Body of epididymis
Tunica vaginalis
Duct of epididymis Cavity of
tunica vaginalis
Tail of epididymis
(a) (b)
Sperm
Seminiferous
tubule
Areolar
connective
tissue
(c) Interstitial Myoid Spermatogenic Sustentocyte
endocrine cells cells in tubule
cells epithelium
Figure 27.3 Structure of the testis. (a) Partial sagittal section to four tightly coiled seminiferous tubules (sem″ĭ-nif′er
through the testis and epididymis. The anterior aspect is to the right. “sperm-carrying”), the actual “sperm factories” consisting
(For a related image, see A Brief Atlas of the Human Body, Figure a thick stratified epithelium surrounding a central flu
73). (b) External view of a testis from a cadaver; same orientation containing lumen (Figure 27.3a and c). The epithelium cons
as in (a). (c) Seminiferous tubule in cross section (270×). Note the of spheroid spermatogenic (“sperm-forming”) cells embed
spermatogenic (sperm-forming) cells in the tubule epithelium and in substantially larger columnar cells called sustentocytes.
the interstitial endocrine cells in the connective tissue between the
sustentocytes are supporting cells that play several roles
tubules.
sperm formation, as described shortly.
Surrounding each seminiferous tubule are three to five la
View histology slides
of smooth muscle–like myoid cells (Figure 27.3c). By contr
>Study Area>
ing rhythmically, myoid cells may help to squeeze sperm
testicular fluids through the tubules and out of the testes.
M27_MARI6971_10_SE_CH27_1046-1093.indd 1049
