Male Reproductive System

Male Reproductive System
• The reproductive
system in men has
components in the
abdomen, pelvis,
and perineum.

• The major components
are a testis, epididymis,
ductus deferens, and
ejaculatory duct on each
side, and the urethra
and penis in the midline.
• Three types of
accessory glands are
associated with the
system:
– A single prostate;
– A pair of seminal
vesicles;
– A pair of bulbourethral
glands.

Male Reproductive System

The scrotum
• The scrotum is an
outpouching of the
lower part of the
anterior abdominal
wall.
• It contains the testes,
the epididymides,
and the lower ends of
the spermatic cords.

The scrotum
• It is divided on its
surface into two
compartments by a
raphé, which is
continued forward to the
under surface of the
penis, and
backward, along the middle
line of the perineum to
the anus.
• Each compartment
contains one of the two
testes, and one of the
epididymides.

The scrotum
• The wall of the scrotum
has the following layers:
– Skin
– Superficial fascia
– Spermatic fasciae
– Tunica vaginalis

The scrotum
Skin
•The skin of the scrotum is
thin, wrinkled, and
pigmented and forms a
single pouch. A slightly
raised ridge in the midline
indicates the line of fusion
of the two lateral
labioscrotal swellings.
Superficial fascia
•This is continuous with the fatty
and membranous layers of the
anterior abdominal wall.
•The fat is replaced by smooth
muscle called the dartos muscle.
•This is innervated by
sympathetic nerve fibers and is
responsible for the wrinkling of
the overlying skin.

The scrotum
Spermatic fasciae
•It has three layers which lie
beneath the superficial fascia and
are derived from the three layers of
the anterior abdominal wall on each
side.
•The external spermatic fascia is
derived from the aponeurosis of the
external oblique muscle; the
cremasteric fascia is derived from
the internal oblique muscle; and,
finally, the internal spermatic fascia
is derived from the fascia
transversalis.
Tunica vaginalis
This lies within the spermatic
fasciae and covers the
anterior, medial, and lateral
surfaces of each testis.

Lymph Drainage of the
Scrotum
• Lymph from the skin
and fascia, including
the tunica vaginalis,
drains into the
superficial inguinal
lymph nodes .

Testes
• Testis has ellipsoid-
shaped.
• Testes develop in the
abdomen and move
before birth into the
scrotum.
• The left testis usually
lies at a lower level
than the right.

Testes
• The testis are covered
by:
• A closed sac of
peritoneum (the tunica
vaginalis), which
originally connected to
the abdominal cavity.
Normally after testicular
descent, the connection
closes, leaving a fibrous
remnant.
• It is covered by a fibrous
capsule called the tunica
albuginea.

Testes
• In the inner surface of the
capsule is a series of fibrous
septa that divide the interior
of the organ into lobules.
• Lying within each lobule are 1
to 3 coiled seminiferous
tubules.
• The tubules open into a
network of channels called
the rete testis.
• Small efferent ductules
connect the rete testis to the
upper end of the epididymis.

Testes

Epididymis
• The epididymis is a
single, long coiled
duct that courses
along the
posterolateral side of
the testis.
• The tunica vaginalis
covers the epididymis
with the exception of
the posterior border.

Epididymis
• Structurally, epididymis
divided into :
– Head
– Body
– tail

Epididymis
It has two distinct components:
–The efferent ductules, which form an enlarged coiled
mass that sits on the posterior superior pole of the testis
and forms the head of the epididymis;
–The true epididymis, which is a single, long coiled duct
into which the efferent ductules all drain, and which
continues inferiorly along the posterolateral margin of the
testis as the body of epididymis and enlarges to form the
tail of epididymis at the inferior pole of the testis.

Arterial Blood Supply of the Testis
and Epididymis
• The testicular artery is
a branch of the
abdominal aorta.

• The testicular veins emerge
from the testis and the
epididymis as a venous
network, the pampiniform
plexus.
• This becomes reduced to a
single vein as it ascends
through the inguinal canal.
• The right testicular vein
drains into the inferior
vena cava, and the left vein
joins the left renal vein.

Lymphatic Drainage of The
Testes
• Lymphatic drainage of
the testes is to the
para- aortic lymph
nodes.

Ductus deferens
• (Latin: "carrying-away
vessel"), also called vas
deferens.
• The ductus deferens is
a long muscular duct
that transports
spermatozoa from the
tail of the epididymis to
the ejaculatory duct.

Ductus deferens course
• The vas arises from the tail of
the epididymis and traverses
the inguinal canal to the deep
ring, passes downwards on
the lateral wall of the pelvis
almost to the ischial
tuberosity and turns medially
to cross the ureter posterior
to the bladder.
• It continues inferomedially
along the base of the bladder,
anterior to the rectum, almost
to the midline, where it is
joined by the duct of the
seminal vesicle to form the
ejaculatory duct.

Ductus deferens course
• The terminal part of
the vas deferens is
dilated to form the
ampulla of the vas
deferens.
• The ejaculatory duct
penetrates through the
prostate gland to
connect with the
prostatic urethra.

Seminal vesicle
• The seminal vesicles
are an accessory gland
of the male
reproductive system .
• The seminal vesicles
are two lobulated
organs about 2 in. (5
cm) long lying on the
posterior surface of the
bladder .

Seminal vesicle
• On the medial side of
each vesicle lies the
terminal part of the vas
deferens.
• Posteriorly, the seminal
vesicles are related to
the rectum.
• Inferiorly, each seminal
vesicle narrows and joins
the vas deferens of the
same side to form the
ejaculatory duct.

Blood Supply of Seminal
vesicle
Arteries
•The arterial blood supply
from, the inferior vesicle and
middle rectal arteries.
Veins
• The veins drain into
the internal iliac veins.

Ejaculatory Ducts
• The two ejaculatory ducts are
each less than 1 in. (2.5 cm)
long and are formed by the
union of the vas deferens and
the duct of the seminal vesicle.
• The ejaculatory ducts pierce
the posterior surface of the
prostate and open into the
prostatic part of the urethra,
close to the margins of the
prostatic utricle; their function
is to drain the seminal fluid
into the prostatic urethra.

Semen
• Semen is a milky white, somewhat sticky mixture of sperm,
testicular fluid, and accessory gland secretions. The liquid
provides a transport medium and nutrients and contains
chemicals that protect and activate the sperm and facilitate
their movement.

Semen contains several substances that
play many roles:
• Prostaglandins decrease the viscosity of mucus guarding the
entry (cervix) of the uterus and stimulate reverse peristalsis in
the uterus, facilitating sperm movement through the female
reproductive tract.
• The hormone relaxin and certain enzymes in semen enhance
sperm motility.
• Contained ATP provides energy.
• Certain ingredients suppress the immune response in the
female’s reproductive tract.

• Antibiotic chemicals destroy some bacteria.
• Clotting factors in semen coagulate it just after it is ejaculated.
Coagulation causes the sperm to stick to the walls of the
vagina and prevents the initially immobile sperm from
draining out of the vagina. Soon after semen coagulates,
fibrinolysin liquefies the sticky mass and the sperm swim out
and begin their journey through the female duct system

The Bulbo-Urethral Glands
• The bulbo-urethral glands are pea-sized glands located
inferior to the prostate in the urogenital diaphragm
• They produce a thick, clear mucus, some of which drains into
the spongy urethra and lubricates the glans penis when
sexually excited.
• The mucus neutralizes traces of acidic urine and lubricates the
urethra just prior to ejaculation.

Prostate
• The prostate is an unpaired
accessory structure of the
male reproductive system
that surrounds the urethra
in the pelvic cavity .
• It lies immediately inferior
to the bladder, above the
urogenital diaphragm,
posterior to the pubic
symphysis, and anterior to
the rectum.

Prostate
• The prostate is shaped like
an inverted rounded cone
with a larger base, which
is continuous above with
the neck of the bladder,
and a narrower apex,
which rests below on the
pelvic floor.
• The inferolateral surfaces
of the prostate are in
contact with the levator
ani muscles that together
cradle the prostate
between them.

Prostate

Prostate
• The two ejaculatory
ducts pierce the upper
part of the posterior
surface of the prostate
to open into the
prostatic urethra at
the lateral margins of
the prostatic utricle.

Relations of Prostate
Superiorly
•The base of the prostate is
continuous with the neck of
the bladder.
•The urethra enters the center
of the base of the prostate.
Inferiorly
• The apex of the prostate
lies on the upper surface of
the urogenital diaphragm.
• The urethra leaves the
prostate just above the
apex on the anterior
surface

Relations of Prostate
Anteriorly
•The prostate is related to the
symphysis pubis.
•The prostate is connected to
the posterior aspect of the
pubic bones by the
puboprostatic ligaments.
Laterally
•The prostate is embraced by
the anterior fibers of the
levator ani.
Posteriorly
•The prostate is closely
related to the anterior
surface of the rectal ampulla
and is separated from it by
the rectovesical septum
(fascia of Denonvilliers).

Structure of the Prostate
• Enclosed within thin dense fibrous capsule
• Inner loose sheath derived from pelvic fascia is prostatic
sheath͟
– Continuous inferiorly with superior fascia of urogenital
diaphragm
– Posteriorly it is part of rectovesical septum
– Separates bladder, seminal vesicles and prostate from
rectum
• Prostatic venous plexus lies between fibrous capsule and
prostatic sheath.

Structure of the Prostate
Prostate divided into:
– Two lateral lobes
– One median lobe
– Anterior and posterior
lobes

Structure of the Prostate
• Anterior
– Tissue lying anterior to urethra
– No glands; fibromuscular tissue only
• Median
– Cone-shaped region between ejaculatory ducts and
urethra
• Lateral (left & right)
– Main mass of gland, continuous posteriorly
– Separated by prostatic urethra
• Posterior
– Describes postero-medial part of lateral lobes
palpable through rectum on DRE.

Functions of Prostate
• During ejaculation, prostatic smooth muscle contracts,
squeezing the prostatic secretion into the prostatic urethra via
several ducts. This fluid plays a role in activating sperm and
accounts for up to one-third of the semen volume. It is a
milky, slightly acid fluid that contains citrate (a nutrient
source), several enzymes (including fibrinolysin,
hyaluronidase, and acid phosphatase), and prostate-specific
antigen (PSA).

Blood Supply of The Prostate
• Arterial supply
– Arteries derived from internal pudenal, inferior vesical and
middle rectal arteries (branches of internal iliac)
• Venous drainage
– Veins form prostatic venous plexus around sides and base
of prostate – located between capsule and sheath
– Drains into internal iliac veins
– Also communicates with vesical venous plexus and
vertebral venous plexuses.

Lymphatics and innervation of
Prostate gland
• Lymphatic drainage
– Lymph vessels terminate in internal iliac and sacral
lymph
• nodes
– Some vessels from posterior surface pass with lymph
• vessels froŵ ďladder to exterŶal iliaĐ LN’s
• Innervation
– Parasympathetic fibres arise from pelvic splanchnic
nerves
– Sympathetic fibres from inferior hypogastric plexuses

Penis
• The penis is a
pendulous organ
suspended from the
front and sides of the
pubic arch and
containing the
greater part of the
urethra.

Penis
• It consists of internal
root, external shaft, &
glans.
– Root: the portion of the
penis that extends
internally into the pelvic
cavity.
– Shaft: the length of the
penis between the glans
and the body.
– Glans: the head of the
penis; has many nerve
endings.
• Foreskin: a covering of
skin over the penile glans.

Penis

Penis
• The root of penis
consists of the two crura,
which are proximal parts
of the corpora cavernosa
attached to the pubic
arch, and the bulb of
penis, which is the
proximal part of the
corpus spongiosum
anchored to the perineal
membrane.

Penis
• The body of the penis is essentially
composed of three cylinders of
erectile tissue enclosed in a tubular
sheath of fascia (Buck's fascia).
• The erectile tissue is made up of
two dorsally placed corpora
cavernosa and a single corpus
spongiosum applied to their ventral
surface .
• At its distal extremity, the corpus
spongiosum expands to form the
glans penis, which covers the distal
ends of the corpora cavernosa.
• On the tip of the glans penis is the
slitlike orifice of the urethra, called
the external urethral meatus.

Penis

External penile structures
• Corona: the rim of the
penile glans.
• Frenulum: thin strip of
skin connecting the
glans to the shaft on
the underside of the
penis.
Both are highly sensitive
areas to the touch

Blood Supply of The Penis
Arteries
•The corpora cavernosa
are supplied by the deep
arteries of the penis ; the
corpus spongiosum is
supplied by the artery of
the bulb.
•In addition, there is the
dorsal artery of the
penis.
•All the above arteries
are branches of the
internal pudendal artery.
Veins
• The veins drain into the
internal pudendal
veins.

Lymphatics and innervation of
The Penis
Nerve Supply
Sensation
•The nerve supply is from
the pudendal nerve and
the pelvic plexuses.
Erectile function
•Parasympathetic(excitat
ory)
•Sympathetic (inhibitory)
Lymph Drainage
•The skin of the penis is
drained into the medial group
of superficial inguinal nodes.
•The deep structures of the
penis are drained into the
internal iliac nodes.

Analagous structures in male
and female sexual anatomy
Male
Glans
Foreskin
Shaft
Clitoris
Clitoral hood
Scrotal sac
Testes
Female
Labia minora
Labia majora
Ovaries

Physiology of the Male
Reproductive System
The chief phases of the male sexual response are
1. Erection of the penis, which allows it to penetrate the female
vagina
2. Ejaculation, which expels semen into the vagina

Erection
• Erection, enlargement and stiffening of the penis, results
from engorgement of the erectile bodies with blood. It
happens because of the parasympathetic function of arteriole.
• Sexual excitement triggers a parasympathetic reflex that
promotes release of nitric oxide (NO) locally.
• Nitric oxide relaxes smooth muscle in the penile blood vessel
walls, dilating these arterioles, and the erectile bodies fill with
blood.

• Expansion of the corpora cavernosa of the penis compresses
their drainage veins, retarding blood outflow and maintaining
engorgement.
• The corpus spongiosum expands but not nearly as much as
the cavernosa. Its function is to keep the urethra open during
ejaculation.
• The erect penis not bend or fold during intercourse. The
longitudinal and circular arrangement of collagen fibers
surrounding the penis prevents this problem.

• Ejaculation
• Ejaculation is the propulsion of semen from the male duct
system.
• Although erection is under parasympathetic control,
ejaculation is under sympathetic control.
• When impulses provoking erection reach a critical level, a
spinal reflex is initiated, and a massive discharge of nerve
impulses occurs over the sympathetic nerves serving the
genital organs

1. The bladder sphincter muscle constricts, preventing
expulsion of urine or reflux of semen into the bladder.
2. The reproductive ducts and accessory glands
contract, emptying their contents into the urethra.
3. Semen in the urethra triggers a spinal reflex through
somatic motor neurons. The bulbospongiosus muscles of
the penis undergo a rapid series of contractions,
propelling semen from the urethra at a speed of up to
500 cm/s (200 inches/s, close to 11 mi/h). These
rhythmic contractions are accompanied by intense
pleasure and many systemic changes, such as generalized
muscle contraction, rapid heartbeat, and elevated blood
pressure.

Spermatogenesis.
• The process of spermatogenesis encompasses the phases
through the production of sperm. Conversion of the haploid
spermatids to sperm cells is specifically called spermiogenesis.
• Throughout spermatogenesis, descendants of the same
spermatogonium remain closely attached to one another by
cytoplasmic bridges. They are also surrounded by and
connected to nonreplicating supporting cells called
sustentocytes or Sertoli cells, which extend from the basal
lamina to the tubule lumen.

PHASES OF SPERMATOGENESIS
• Spermatogonial Phase (Mitosis)
• Spermatocyte Phase/Spermatocytosis (Meiosis)
• Spermatid Phase (Spermiogenesis)
64

PHASE I-Spermatogonial Phase
65

PHASE II-SPERMATOCYTOSIS
66
Spermatids

PHASE II- MEOSIS
67
Prophase-22 days
Largest cell

PHASE III-(SPERMIOGENESIS)
68

SPERMATOGENESIS
Cytokinesis is incomplete
Spermatogonial
Phase
Spermatocyte
phase
Spermiogenesis
phase
69

SPERMATOGENESIS
Cytokinesis is incomplete
Spermatogonial
Phase
Spermatocyte
phase
Spermiogenesis
phase
70

The sustentocytes:
• Provide nutrients and essential signals to the dividing cells,
even telling them to live or die
• Move the cells along to the lumen
• Secrete testicular fluid (rich in androgens and metabolic
bacids) that provides the transport medium for sperm in the
lumen
• Phagocytize faulty germ cells and the excess cytoplasm
sloughed off as the spermatids transform into sperm
• Produce chemical mediators (inhibin and androgen-binding
protein) that help regulate spermatogenesis

Transformation of a spermatid intoa
functionalsperm.
The stepwise process of spermiogenesis:
1. The Golgi apparatus packages the acrosomal enzymes,
2. The acrosome forms at the anterior end of the nucleus and
the centrioles gather at the opposite end of the nucleus,
3. Microtubules elaborate to form the flagellum,
4. Mitochondria multiply and take up position around the
proximal portion of the flagellum, and
5. Excess cytoplasm sloughs off.
6. Structure of an immature sperm than has just been released
from a sustentocyte.
7. Structure of a fully mature sperm.