THE MALE REPRODUCTIVE SYSTEM

Components
• This is made up of :
– 1. scrotum
– 2. testes
– 3. spermatic cord
– 4. prostate gland
– 5. seminal vesicles
– 6. penis
– 7. bulbourethral glands
– 8. urethra
 Scrotum
• The scrotum is a pouch made up of:
– Skin
– connective tissue
– smooth muscle.
• The scrotum is divided into two (2)
compartments.
• Each compartment contains:
– One testis
– One epididymis
– Testicular end of the spermatic cord.
 Testes -1
• These are the male gonads (equivalent to the
ovaries in females).
• They are responsible for producing of:
– 1. sperms
– 2. hormones
• The surrounding wall of each testis is made up of:
– Outer: Tunica vaginalis
– Middle: Tunica albuginea
– Inner: Tunica vasculosa
 Testes -2
• The smooth muscle layer of the scrotum is called
the cremaster muscle.
• The tunica vaginalis is the outermost layer
derived from peritoneum, and it covers the tunica
albuginea.
• The tunica albuginea is a fibrous layer which
grows into the testes and divides the testes into
lobules.
• The tunica vasculosa consists of a network of
capillaries in connective tissue.
 Testes -3
• Each testis is made up of about 200-300 lobules.
• Each lobule is made up of germinal epithelium
called Seminiferous tubules. These tubules
produce spermatozoa.
• Found in between these tubules are the Leydig
cells which produce the hormone testosterone
(at puberty).
• There are also foldings of the seminiferous
tubules that form a single mass, that is found on
the upper pole of each testis. This is the
epididymis.
• The epididymis matures and stores spermatozoa.
 Sperm
• A mature sperm is made up of:
– A head (filled by nucleus)
– A body (packed with mitochondria)
– A long whip-like tail (for motility)
• The testes hang outside the pelvic cavity, and
the scrotum has a thin wall. These factors
allow for successful spermatogenesis at a
temperature about 3 degrees Celsius below
the normal body temperature.
 Spermatic cord
• This suspends the testes in the scrotum.
• Components of the spermatic cord:
– Testicular artery
– Testicular vein
– Testicular nerves
– Lymphatic vessels
– Vas deferens/spermatic duct
• A sheath of smooth muscle covers the spermatic
cord as it extends from the testes through the
inguinal canal.
 Blood Supply To The Testes
• Oxygenated blood is carried to the testes via
the TESTICULAR ARTERY which is a direct
branch of the abdominal aorta.
• Deoxygenated blood is carried away from the
testes by the TESTICULAR VEIN.
• NB: The left testicular vein drains into the left
renal vein first, whereas the right testicular
vein drains directly into the inferior vena cava.
 Vas Deferens
• This passes from the testes, through the
inguinal canal, towards the posterior wall of
the bladder, and to then to duct of the
seminal vesicle.
• The vas deferens joins the duct of the seminal
vesicle to become the EJACULATORY DUCT .
• The ejaculatory ducts pass through the
prostate gland and join the prostatic urethra.
 The Seminal Vesicles
• These are two (2) small fibromuscular
pouches.
• They release seminal fluid during ejaculation.
• The seminal fluid forms about 60% of
ejaculated semen.
• Seminal fluid provides nutrients to support
sperm motility.
 Prostate Gland
• This lies in the pelvic cavity in front of the rectum.
• It surrounds the first part of the urethra.
• It has an outer fibrous capsule.
• It has large amounts of smooth muscle.
• It has glandular substance covered with columnar
epithelium.
• It releases a milky fluid that forms 30% of the
ejaculated semen.
• It contains an enzyme that makes semen thicken
in the vagina.
 Urethra
• This is made up of three (3) parts:
– Prostatic urethra (passes through the prostate gland)
– Membranous urethra (shortest and narrowest)
– Penile urethra (lies within corpus spongiosum)
• This serves as a common pathway for the flow of urine
and semen.
• The internal urethral sphincter is made up of smooth
muscle, and is found at the neck of the urinary bladder.
• The external urethral sphincter is made up of skeletal
muscle, and is found at the membranous urethra.
 Penis -1
• The penis is made up of a root and a body.
• The root of the penis lies in the perineum.
• The body of the penis surrounds the urethra.
• The penis is made up of three (3) cylindrical
masses composed of erectile tissue and smooth
muscle.
• The erectile tissue has a rich supply of blood.
• The cylindrical masses are:
– 2 corpora cavernosa
– 1 corpus spongiosum
 Penis -2
• The corpora cavernosa are found lateral, whereas the
corpus spongiosum is found between them.
• The corpus spongiosum has the urethra passing
through it.
• The tip of the penis is expanded into a triangular
structure called the glans penis.
• Just above the glans penis is the prepuce (foreskin)
which is a skin that folds upon itself and forms a
moveable double layer.
• The arterial blood supply to the penis is from the deep,
dorsal and bulbar penile arteries which are branches
from the internal pudendal artery.
• Venous drainage is via the internal pudendal vein.
 Penis -3
• The parasympathetic nervous stimulation of the
penis results in filling of the erectile tissue with
blood. The penis then becomes engorged and
erect.
• The expulsion of semen from the penis is called
ejaculation. There is contraction of the smooth
walls of the vas deferens, via sympathetic
nervous stimulation.
• Semen is slightly alkaline, and about 2-5mls of
semen are produced in a normal ejaculate. 1ml of
semen contains about 40-100 million
spermatozoa.
 Bulbourethral Glands
• These are small glands found at the base of
the penis.
• They are found posterior and lateral to the
membranous urethra.
• They secrete pre-ejaculate fluid during sexual
arousal.
• They are the equivalent of the Bartholin’s
glands in females.
 At Puberty
• Follicle stimulating hormone from the anterior
pituitary gland acts on the seminiferous
tubules to produce spermatozoa.
• Luteinizing hormone from the anterior
pituitary gland acts on the Leydig cells to
produce the hormone testosterone.
 Assignment
• 1. What is oligospermia?
• 2. What is cryptorchidism?
• 3. List 5 developmental changes influenced by
the production of testosterone at puberty
• 4. What is phimosis?
• 5. What is a hydrocoele?