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No. 12
1. Introduction of the Genital System
2. Male Genital System
Chapter 5 The Genital System
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The introduction of the genital system:
Functions: The organs of the male and
female reproductive system ensure the
continuance of the species. They do this
by producing gametes, or germ cells, and
by providing a method by which the
gametes of the male (sperm) can be
introduced into the body of the female,
where one of them joins with a gamete
(ovum) of the female.
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Constitutions: The genital (or
reproductive) system includes the male
and the female genital organs. Both
systems are composed of internal and
external genital organs.
The internal genital organs consist of
gonad, reproductive canals and accessory
glands.
The external genital organs are mainly
copulatory organs.
Table 1: The components of male
and female reproductive systems
Divisions
Internal
genital organs
Male genital organs
Female genital
organs
Gonad
Testis
Ovum
Reproductive
canals
Epididymis, Ductus
deferens, Ejaculatory
duct, Urethra
Uterine tube,
Uterus, Vagina
Accessory
glands
Seminal vesicle,
Prostate, Bulbourethral
gland
Greater
vestibular gland
(Bartholin gland)
Scrotum, Penis
Vulva (Female
pudendum)
External genital organs
Section 1 The Male Genital
Organs
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Composition:
The male genital organs are composed
of internal and external genital organs.
1. The internal male genital organs
consist of:
Gonad—testes
Reproductive canals (epididymis, ductus
deferens, ejaculatory duct, urethra)
Accessory glands (seminal vesicle,
prostate gland, bulbourethral gland).
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The testes produce sperms, which are
stored in the epididymides. During
ejaculation the sperms pass through the
ductus deferens, ejaculatory ducts and
urethra to be expelled from the body.
The accessory glands secrete the fluid to
be added to the seminal fluid to maintain
the nutrition and activity of the sperms.
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2. The external male genital
organs are the scrotum and penis.
The penis is the copulatory organ by
which the sperms are introduced into
the female genital tract.
The scrotum houses the testes and
epididymides.
Ⅰ. The Internal Genital Organs
Ⅰ) The Testes
 The testes are male gonads,
producing gametes of the male
(sperms) and male hormones. They
average 4-5 cm in length and weight
20-30 g.
1. The location of testes

The testes are paired oval-shaped
organs, being housed in the scrotum.
2. The features of testes
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Each testis has the superior and
inferior extremities, the lateral and
medial surfaces, and the anterior and
posterior borders.
The blood vessels, nerves and
lymphatics pass through the
posterior border to enter or leave the
testis. The posterior border connect
with the epididymis.
3. The structure of testes
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The testes are covered by a dense layer of
fibrous membrane, the tunica albuginea.
It is thicker on the posterior border of the
testis and form the mediastinum testis,
which gives off the septula testis
extending inward to divide each testis into
a series of compartments (100-200) called
lobules of testis.
Each lobule contains two to four tiny
coiled tubules, the convoluted
seminiferous tubules, that produce the
sperms by a process called
spermatogenesis.
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In the mediastinum testis the convoluted
seminiferous tubules join to form the
straight seminiferous tubules which
enter the fibrous tissue of the
mediastinum testis. They then form the
rete testis. At the upper end of the
mediastinum testis the rete testis
terminate in 12～15 efferent ductules of
testis, passing from the testis to the
epididymis.
4. The function of testes

After puberty the testes produce
sperms and secrete male hormone.
Ⅱ) The Epididymis
1. Location of epididymis
 It is attached to the superior
extremity and the posterolateral
surface of the testis.
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2. Morphological feature of epididymis
The epididymis is comma—shaped and is divided
into the head, body and tail.
Head: The enlarged superior portion of the
epididymis is known as the head.
Body: The portion posterior to the testis is called
the body.
Tail: The inferior portion is referred to as the tail.
The head of the epididymis contains the efferent
ductules which terminate in a coiled duct of
epididymis within the body and tail. The end of
the duct of epididymis passes upward to continue
with the ductus deferens.
3. Function of epididymis
 The epididymis is the principal
store—house for sperms. It also adds
an essential secretion to the seminal
fluid in which the sperms are
developed and activated.
Ⅲ) The Ductus Deferens
It is a continuation of the duct of
epididymis, about 50 cm long. The
ductus is divided into four parts:
1. The testicular part
 It begins at the tail of epididymis,
and ascends on the medial side of
the epididymis, posterior to the testis.
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2. The funicular (spermatic) part
 It extends from the superior
extremity of the testis to the
superficial inguinal ring.
 It lies in medial and posterior portion
of the spermatic cord and can be
palpated easily in the living body.
 This part is the place where the
vasectomy is performed.
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3. The inguinal part
It passes through the inguinal canal
from the superficial ring to the deep
ring.
4. The pelvic part
 It enters the abdominal cavity from the deep ring
of the inguinal canal. Then passes downward and
medially along the lateral wall of the pelvis. It
crosses over the terminal portion of the ureter
anterosuperioly to its medial side.
 The terminal portion of the ductus dererens is
dilated, and called the ampulla ductus
deferentis as it descends behind the fundus of
the bladder. Its end is thin and joins the
excretory duct of the seminal vesicle to form the
ejaculatory duct.
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The Spermatic Cord
When the testis descends through
the abdominal wall into the scrotum,
it carries its vessels and nerves and
ductus deferens with it. These
structures meet at the deep inguinal
ring and together form the
spermatic cord.
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It extends from superior extremity of
the testis to the deep inguinal ring,
11～15 cm in length.
The main structures of spermatic
cord are the ductus deferens,
testicular artery, pampiniform plexus
of vein, nervous plexus, lymphatic
vessels and the vestige of vaginal
process.
Ⅳ) The Ejaculatory Duct
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It is formed by the union of the
terminal part of the ductus deferens
and the excretory duct of seminal
vesicle.
It commences at the base of prostate,
and passes downward and forward to
open into the prostatic portion of the
urethra.
Ⅴ) The Seminal Vesicles
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They are two oval sacculated organs
placed posterior to the fundus of urinary
bladder, lateral to the ampulla ductus
dererentis and in front of the rectum.
Its excretory duct joins the corresponding
ductus deferens to form the ejaculatory
duct.
The secretion of the seminal vesicles is a
component of seminal fluid.
Ⅵ) The Prostate
It is a single, firm gland consisting of
muscular and glandular tissues.
Function:
 Its secretion, the important
component of the seminal fluid, is
conveyed into the prostatic portion of
urethra through 16～32 excretory
ducts.
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1. Location
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The prostate lies in the lesser pelvic
cavity, below the urinary bladder and
around the superior part of the
urethra, between the bladder and
the urogenital diaphragm. It is in
front of the rectum, posterior to the
pubic symphysis.
2. External Features:
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The prostate is chestnut-shaped and has an apex,
a base.
The apex of prostate is inferior and rests on the
urogenital diaphragm.
The base is superior and is against the neck of
bladder.
The urethra passes through the prostate.
The anterior surface of prostate is posterior to
the pubic symphysis.
There is a shallow sulcus, called prostatic
sulcus, along the midline of the posterior surface.
This sulcus, apmula ductus deferentis and
seminal vesicles can be palpated through the
anterior wall of the rectum in the living body.
The lobes of prostate:
 The prostate may be divided into five
lobes:
 anterior, median, posterior and two lateral
lobes.
 The median lobe (isthmus of prostate) lies
behind the urethra, between the right and
left lobes, in front of the posterior lobe.
 In old men, the prostate sometimes
enlarges and bulges into the lumen of
urethra causing obstruction of it.
Ⅶ) The Bulbourethral Glands (of
Cowper)

They are about the size of pea, one
on each side of the membranous part
of urethra, embedded in the deep
transverse muscle of perineum. Their
excretory ducts open into the upper
part of the spongy part of urethra.
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The seminal fluid is the mixture of
the sperms and secretion of
accessory glands. It is white milk like
fluid, with weak alkalinity. In every
ejaculation about 2～5 ml of seminal
fluid is expelled, which contains
300～500 million of sperms
Ⅱ. The External Genital Organs
Ⅰ) The Scrotum
 It is a pendulous pouch of skin and
superficial fascia evaginated from the
lowed part of the abdominal wall.
 The scrotal wall is composed of skin
and dartos.
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① The skin: The skin is thin and extensible,
which contains few hairs, but many sebaceous
and sweat glands, pigment cells and nerves.
② The dartos: Involuntary muscle fibers lie
within the superficial fascia of the scrotum to
form the dartos. The contraction of dartos causes
the scrotal skin wrinkle when cold. Beneath the
dartos there are three layers of tunics to enclose
the testis and spermatic cord, that is the external
spermatic fascia, the cremaster and the internal
spermatic fascia.
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③ The external spermatic fascia: It is
the continuation of the aponeurosis of the
obliquus externus abdominis.
④ The cremaster: It is the middle layer
coming from the obliquus internus
abdominis and transversus abdominis.
⑤ The internal spermatic fascia: It is
the continuation of the transverse fascia.
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⑥ The tunica vaginalis of testis: It is from the
peritoneum. The tunica vaginalis is the remnant
of the lower end of the vaginal process, the upper
part of which is obliterated. The tunica vaginalis
consists of visceral layer and perietal layer.
Between these two layers there is a serous cavity
with few fluid in it. If the upper part of the
vaginal process is not obliterated, the serous
cavity of testis communicates with the abdominal
cavity, and the herniated abdominal content,
such as loop of ileum will enter the serous cavity
close to the testis. This case is called the
congenital indirect inguinal hernia.
Ⅱ) The Penis
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It is the male organ of copulation and urination.
It comprises a root, a body and a head.
The root of penis is the posterior portion and
attaches to the pubic arch.
The body continuing with the root is the movable
part, and is covered with skin and fascia.
The head of penis is a slightly enlarged portion
called the glans penis, which is separated from
the body by a constriction, the neck of penis. A
median slit at the tip of the glans is the external
orifice of urethra.
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At the neck, the skin is folded upon itself to form
the prepuce. The free border of the prepuce is
called the orifice of prepuce. The prepuce in
the child is longer than in the adult, and the
diameter of the orifice of prepuce is smaller than
in adult. In some cases, the prepuce is longer
than normal (redundant prepuce) or the orifice of
prepuce is smaller than normal and the prepuce
cannot be retracted over the glans (phimosis).
This may permit accumulation of the secretions
beneath the prepuce, leading to inflammation.
And it is now generally believed that chronic
inflammation of the prepuce predisposes to
carcinoma of the glans penis. For these reasons
prophylactic circumcision is commonly practiced.
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The frenulum of prepuce is a median fold
passing from the deep surface of the prepuce to
a point near the external orifice of urethra
ventrally. It must be protected during
circumcision.
Structure of the penis:
Structurally the penis is composed of three
cylindrical masses of erectile tissue.
Cavernous body of penis: The two dorsally
located masses are called the cavernous body of
penis.
Cavernous body of urethra: The single smaller
ventral mass, the cavernous body of urethra,
contains the spongy part of the urethra.
Ⅲ) The Male Urethra
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It extends from the internal orifice of
urethra in the urinary bladder to
external orifice at the end of the
penis. It is 17—20 cm long and may
be divided into three parts:
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1. The prostatic part
It is about 2.5 cm in length with the
largest caliber.
On the midline of posterior wall there is a
longitudinal ridge, urethral crest. At the
middle portion of the urethral crest there
is a small prominence, seminal colliculus,
lateral to which is the opening of
ejaculatory duct. The prostatic ductules
open into the urethra near the crest.
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2. The membranous part
It is 1—2 cm in length, and is the shortest, least
dilatable and narrowest part of the urethra. It is
within the urogenital diaphragm, and surrounded
by the sphincter of urethra.
This striate muscle is under voluntary control
after early infancy.
Anterior ruethra and posterior urethra:
In the clinic the first and second parts of urethra
are called the posterior urethra, and the last
spongy part the anterior urethra.
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3. The cavernous (spongy) part
It is contained in the cavernous body of
urethra, about 15 cm in length. It extends
from the end of the membranous part to
the external orifice of urethra.
In this part there are two dilated places.
One is at the proximal portion within the
bulb of penis, called the bulbous portion of
urethra, which is the common site of
rupture in straddle injuries. The other is
near the external orifice of urethra, the
navicular fassa.
The male urethra presents three
strictures, three dilatations and two
curvatures.
Three strictures:
The three strictures are situated in:
 ① The internal urethral orifice,
 ② The membranous portion
 ③ The external orifice of urethra.
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Three dilatations:
The three dilatations are situated in:
 ① The prostatic part of urethra.
 ② The bulbous portion of urethra
 ③ Navicular fossa of urethra.
Two curvatures:
 When the penis is flaccid, the urethra
has a course of the letter “S”.
 ① The subpubic curvature is a
ventrally and upwards concave curve.
 ② The prepubic curvature is a
dorsally and downwards concave
curve.