DEVELOPMENT OF UROGENITAL SYSTEM:
• The urinary and genital system develops from –
Intermediate mesoderm and
• After the formation of the
peritoneal cavity intermediate
mesoderm forms a bulging on
the posterior abdominal wall
later to the attachment of
dorsal mesentry known as the
The medial part of the
urogenital ridge later forms
the genital system and
The lateral part later develops
into nephrogenic cord
• It is the part of the hindgut caudal
• It is divided by the urorectal
septum into –
dorsal primitive rectum and
ventral primitive urogenital sinus
DEVELOPMENT OF KIDNEYS
• The primitive kidney is known
as the pronephros formed in
relation with the cervical
region of the nephrogenic
• This is followed by
appearance of mesonephros
in thoracolumbar region and
finally the formation of
metanephros in the sacral
• The ureteric bud from cloaca grows
cranially, the dilated end is called as
• Ampulla divides to form the pelvis,
further division leads to development
of major calyces then minor calyces
and collecting tubules
• The cells of the ampulla in contact
with the metanephric blastema
undergo differentiation to form the
• The definitive human kidney is derived from the metanephros and lies in the sacral
region in the initial stages of development.
• The kidney ascends from the sacral region to the lumbar region , and in the beginning
the hilum which faces anteriorly rotates and then faces medially
• During ascent, the kidneys pass through the fork like interval between the right and left
umbilical arteries. If the arteries come in the way of ascent, the kidney may remain in
the sacral region.
• The kidneys lie on the posterior abdominal
wall, behind the peritoneum, opposite
12th thoracic and upper three lumbar
• The right kidney lies at a slightly lower
level than the left one due to the
presence of liver on the right side
• The kidney is encased by a fibrous capsule
and surrounded by perinephric fat, which
is enveloped by Gerota fascia
Each kidney presents the
following external features:
1. Two poles (superior and
2. Two surfaces (anterior and
3. Two borders (medial and
4. A hilum.
HILUM OF THE KIDNEY
The medial border (central part) of the kidney
presents a deep vertical slit called hilum. It
transmits, from before backward, the following
1. Renal vein.
2. Renal artery.
3. Renal pelvis.
4. Subsidiary branch of renal artery.
5. In addition to the above structures the hilum also
transmits lymphatics and nerves, the latter being
sympathetic and mainly vasomotor in nature.
CAPSULES OF THE KIDNEY
From within outwards, the kidney is
surrounded by four
capsules/coverings as follows:
1.Fibrous capsule (true capsule).
2. Perirenal (perinephric) fat.
3. Renal fascia (false capsule).
4. Pararenal (paranephric) fat.
• An outer cortex and an inner medulla.
• The cortex is located just below the renal capsule
and extends between the renal pyramids as renal
columns (columns of Bertini).
• The cortex appears pale yellow with granular
• The medulla is composed of 5–11 dark conical
masses called renal pyramids (pyramids of
• The apices of renal pyramids form nipple-like
projections—the renal papillae which invaginate
the minor calyces.
• The nephron is the structural and
functional unit of kidney.
• Each nephron consists of a
glomerulus and a tubule system.
• The glomerulus is a tuft of
capillaries surrounded by Bowman’s
• The tubular system consists of the
proximal convoluted tubule, loop of
Henle, and distal convoluted
• Each collecting tubule begins as a
junctional (connecting) tubule from
the distal convoluted tubule.
• Many collecting tubules unite
together to form collecting duct
(duct of Bellini) which opens on the
apex of renal papilla.
• The collecting tubules radiate from
the renal pyramid into the cortical
region to form radial striations
called THE MEDULLARY RAYS
• The renal arteries arise directly from the abdominal
aorta just below the origin of the superior mesenteric
artery (i.e., at the level of intervertebral disc between
L1 and L2).
• At or near the hilum of the kidney, each renal artery
divides into anterior and posterior divisions.
• The anterior division supplies apical, upper, middle, and
lower segments, while posterior division supplies only
• Segmental arteries Lobular arteries
• The lobar arteries break up into two or
three interlobar arteries which pass through
renal columns between the pyramids.
• When an interlobar artery reaches the base
of the associated pyramids, it divides
dichotomously into the arcuate arteries
• The arcuate arteries run parallel to the
surface of the kidney between the pyramids
and the overlying cortex.
• The venous blood from the kidneys is drained by the renal veins
(right and left)
• The left renal vein passes in front of the aorta immediately to
drain into IVC
• Each kidney is supplied by the renal plexus of nerves which reach
the kidney along the renal artery.
• The renal plexus consists of both sympathetic and
• The sympathetic fibres are derived from T10–L1 spinal segments,
the parasympathetic fibres are derived from both vagus nerves
• The Right kidney drains predominantly into
interaortocaval lymph nodes, and
• The Left kidney drains exclusively to the para-aortic lymph nodes.
DEVELOPMENT OF URINARY BLADDER
• The part of the urogenital sinus above the openings of the
mesonephric ducts is called the vesicouretheral canal
• It has a wider upper part and a narrow lower part the allantois
opens into the wider upper part
• Urinary bladder develops from dilated part of
vesicourethral canal including the proximal part
of the allantois.
• The narrow lower part becomes the primitive
• Absorption of mesonephric ducts and ureteric
buds in the posterior wall of bladder forms the
trigone of the bladder
• The urinary bladder is a muscular
reservoir of urine, lying in the
anterior part of the pelvis
• When the bladder is empty it lies
entirely within the lesser pelvis but
when it becomes distended with
urine, it expands upward and forward
into the abdominal cavity
It is tetrahedral in shape when empty
ovoid in shape when distended.
CAPACITY OF URINARY BLADDER
• Normally in adult male the capacity varies from 120 to 320 ml
• The mean capacity is about 220 ml
An empty and contracted bladder is
tetrahedral in shape and presents the
following external features:
4. Three surfaces (superior and two
5. Four borders (anterior, posterior and
• The mucosal lining of the bladder
comprises a transitional
epithelium that extends from the
renal pelvis to the urethra.
• The most common tumors arising
from Bladder are transition cell
carcinomas (or urothelial)
carcinomas (TCC or UC).
• The principal arteries supplying
blood to the bladder are superior
and inferior vesical arteries which
are the branches of anterior
division of internal iliac arteries.
• The other arteries which make
small contribution in supplying
the lower part of the bladder are:
Obturator and inferior gluteal
• The veins of the bladder do not follow the arteries. They form a
complicated plexus on the inferolateral surfaces near the prostate
called vesical venous plexus
• This plexus passes backward in the posterior ligaments of the
urinary bladder to drain into the internal iliac veins
• The lymphatics of the bladder drain
chiefly into the external iliac lymph
• Some lymph vessels also drain into
the internal iliac lymph nodes
including nodes in the obturator
• The sympathetic innervation (T11,T12 and L1,L2) is responsible
for the filling of the bladder
• The parasympathetic innervation (S2,S3,S4) for the emptying of
• The somatic innervation (Pudendal Nerve – S2,S3,S4) is responsible
for voluntary control of micturition.
DEVELOPMENT OF URETER
• The lower ends of the mesonephric ducts open into that part of
the cloaca that forms the urogenital sinus.
• The ureteric buds arise from the mesonephric ducts, a little
cranial to the cloaca.
• The ureter is derived from the part of the ureteric bud that lies
between the pelvis of the kidney, and the vesicourethral canal.
• The ureter is a narrow,
muscular tube which
conveys urine from the
kidney to the urinary
• Length: 25 cm (10 inches).
Diameter: 3 mm.
ARTERIAL SUPPLY OF URETER
The ureter derives its arterial supply
from the branches of all the arteries
related to it. The important arteries
supplying ureter are:
1. Renal. 2. Testicular or ovarian. 3.
Direct branches from aorta. 4. Internal
iliac. 5. Vesical (superior and inferior).
6. Middle rectal. 7. Uterine.
VENOUS, LYMPHATIC DRAINAGE AND NERVE
• The venous blood from the ureter is drained into the veins
corresponding to the arteries.
• The lymph from the ureter is drained into lateral aortic and iliac
• NERVE SUPPLY : The afferent fibres travel with both sympathetic
(T12-L1) and parasympathetic nerves (S2-S4)
The male urethra is about 18–20 cm long.
1. Prostatic part (passes through the prostate).
2. Membranous part (passes through the urogenital diaphragm).
3. Spongy or penile part (passes through the corpus spongiosum of penis).
DEVELOPMENT OF URETHRA
• Prostatic urethra and membranous urethra are derived from pelvic
part of definitive urogenital sinus
• The penile part is derived from the epithelium of the phallic part
of urogenital sinus.
• It extends from the internal urethral orifice at the
neck of the urinary bladder to the external
urethral orifice (EUO) at the tip of the glans
• In flaccid state of the penis, the long axis of the
urethra presents two curvatures and is therefore
• In erect state of the penis, the distal curvature
disappears and as a result it becomes J-shaped
DEVELOPMENT OF PROSTATE
• The gland develops from numerous buds that arise from the
epithelium of prostatic urethra i.e. caudal part of vesicourethral
canal and from pelvic part of definitive urogenital sinus
• These buds form the secretory epithelium of the gland.
The buds from mesodermal part of the prostatic urethra form the
inner glandular zone and
those arising from the rest of the prostatic urethra (endoderm),
form the outer glandular zone.
• Outer zone differentiates earlier than the inner zone hence is the
site of frequent carcinomatous changes in later life while the
inner zone is affected while the senile hypertrophy of the organ.
• The prostate is a pyramidal-shaped,
fibromuscular glandular organ which
surrounds the prostatic urethra.
Weight: 3 g.
Width (at base): 4 cm.
Length: 3 cm.
Thickness: 2 cm
LOBES OF PROSTATE
• The prostate is divided into five
• 1. Anterior lobe (isthmus): lies in
front of urethra, connects two
• 2. Posterior lobe: lies behind
ejaculatory ducts and median
lobe(primary carcinoma begins in
• 3. Median lobe: It contains much of
the glandular tissue and is a
common site of adenoma.
• 4. Two lateral lobes: The lateral
lobes lie one on each side of the
urethra, contain some glandular
tissue, adenoma may arise in old
• Zonal anatomy has essentially replaced
lobar anatomy of the prostate.
• There are four zones of the prostate –
the peripheral zone (PZ),
transition zone (TZ),
central zone, and
anterior fibromuscular stroma zone.
• The central zone that surrounds the ejaculatory ducts has marked
histologic differences from the PZ.
• It is the PZ, extending across the entire posterior surface of the gland,
that is palpated on rectal examination and is the location of most
• The TZ is the location of benign prostatic hypertrophy
• In young men, the PZ is the prominent zone, whereas the TZ becomes
the dominant zone with age.
STRUCTURES WITHIN THE PROSTATE
• These are as follows:
• 1. Prostatic urethra traverses vertically downward through the
gland at the junction of its anterior one-third and posterior two-
third and opens on the anterior surface just above the apex.
• 2. Ejaculatory ducts traverse the gland posterolateral to the
median lobe and open in the urethra.
• 3. Prostatic utricle is a mucous cul-de-sac about 6 mm long which
extends upward and backward from the prostatic urethra, behind
the median lobe.
CAPSULES OF PROSTATE
The prostatic capsules are two in number in normal
gland and three in number if gland is affected by
benign hypertrophy of the prostate.
1. True capsule: It is formed by the condensation of
peripheral fibrous stroma of the gland, hence
intimately related to the gland.
2. False capsule (prostatic sheath): It is derived
from the pelvic fascia. It is outside the true capsule
and envelops the prostate gland and urinary bladder
in the same compartment
3. Surgical/pathological capsule: When the adenoma
of the gland enlarges, the peripheral part of the
organ becomes compressed. This compressed part of
the gland is called surgical or pathological capsule.
SUPPORTS OF THE PROSTATE
• These are:
• 1. Urogenital diaphragm
• 2.Two pairs of puboprostatic ligaments
• 3. Rectovesical fascia of Denonvilliers: It is a fascial septum
between prostate and ampulla of the rectum.The carcinoma
prostate only rarely penetrates this fascial barrier so that
involvement of the rectum is unusual.
• ARTERIAL SUPPLY: The prostate gland is supplied by the branches
middle rectal, and
internal pudendal arteries.
• The veins from the prostate form a rich venous plexus around the sides and base
of the gland and occupy the space between the true and false capsules.
• The mode of venous drainage from the prostatic venous plexus follows two
1. Into internal iliac veins through the posterior ligaments of the urinary bladder.
2. Into internal and external vertebral venous plexus (of Batson) through veins
passing through anterior sacral foramina.
The communication between the vesical and vertebral venous plexuses is
• The lymphatics from the prostate drain into –
external iliac, and
sacral groups of the lymph nodes.
• With an increasing number of patients being diagnosed in earlier stages (as a
result of screening PSA), there has been a decreased incidence of lymph node
metastases in patients with clinical stage T1c and T2 tumors.
• In the low-risk prostate cancer patients, the risk of lymph node involvement is
generally considered <10%
• The seminal vesicles are two coiled
sacculated tubes about 2 inches (5 cm) long
• They lie extraperitoneally on each side, at
the base of the urinary bladder, in front of
• The lower narrow end of seminal vesicle
(duct of seminal vesicle) joins the ductus
deferens to form the ejaculatory duct.
• The seminal vesicles, as their name
implies, do not form a reservoir for
• Their secretions form a large amount of
the seminal fluid. The secretion of seminal
vesicles is slightly alkaline, containing
fructose, choline, and a coagulating
enzyme called vesiculose
• EJACULATORY DUCTS: There are two ejaculatory
ducts one on each side of the median plane at the
lower part of the bladder base
• Each duct traverses anteroinferiorly through the
upper posterior half of the prostate and along the
side of prostatic utricle to open in the posterior
wall of prostatic urethra on the seminal colliculus
VASA DEFERENTIA (DEFERENT DUCTS)
• These are two in number (right
• Each vas deferens is a thick-
walled muscular tube which
transports spermatozoa from
the epididymis to the
DEVELOPMENT OF EXTERNAL GENITALIA
• With the formation of the
urorectal septum, the cloacal
membrane comes to be
subdivided into –
ventral, urogenital membrane,
a caudal anal membrane.
• The urogenital membrane becomes
elongated in a craniocaudal direction. The
mesoderm on either side of it is soon
heaped up to form two longitudinal
elevations called the primitive urethral
• In addition to these folds, three other
elevations of mesoderm are soon apparent.
• These are: the genital tubercle which is
situated in the midline between the
urogenital membrane and the lower part of
the anterior abdominal wall; and the right
and left genital swellings .
• The genital tubercle becomes cylindrical and
is now called as the phallus
• The phallus undergoes great enlargement to
form the penis
• The prepuce is formed by reduplication of
ectoderm covering distal part of the phallus.
Penis: consists of three masses of vascular
erectile tissue; these are the-
paired corpora cavernosa and
midline corpus spongiosum, which are bounded
by tunica albuginea.
Consists of a root, which includes two crura and
the bulb of the penis;
Body, which contains the single corpus
spongiosum and the paired corpora cavernosa.
Head called the glans penis, which is formed by
the terminal part of the corpus spongiosum and
is covered by a free fold of skin, the prepuce.
The prominent margin of the glans
penis is the corona, the median slit
near the tip of the glans is the
external urethral orifice, and
the terminal dilated part of the
urethra in the glans is the fossa
Preputial glands are small sebaceous
glands of the corona, the neck of the
glans penis, and the inner surface of
the prepuce, which secrete smegma
Supports of penis
The ligaments support the weight of the free
pendulous part (body) of the penis. They are
two in number
1. Fundiform ligament: It springs from the
lower part of the linea alba and splits into
two lamellae, which enclose the proximal
part of the body of penis and then unite
on its urethral aspect with the septum of
2. Suspensory ligament: It is deep to the
fundiform ligament and triangular in shape.
Its narrow upper end is attached in front of
the pubic symphysis and broad lower part
blends with Buck’s fascia (fascia of penis) on
either side of the body of penis.
Arterial supply of
The arteries that supply the penis are:
1. Deep artery of the penis
2. Dorsal arteries of the penis.
3. Arteries of the bulb.
4. Superficial dorsal arteries of penis.
Out of these, the first three pairs of
arteries arise from internal pudendal
arteries, branches of anterior divisions
of internal iliac arteries,
while the last pair arises from
superficial external pudendal arteries,
branches of femoral arteries
• Two veins mainly drain the venous
blood from the penis:
• Superficial dorsal vein of the penis.
• Deep dorsal vein of the penis.
• The main veins contrary to the
arteries lie in the midline separated
from each other by the deep (Buck’s)
fascia of penis.
• Lymph vessels from the
glans penis drain into the
deep inguinal lymph
nodes, especially into the
lymph node of Cloquet.
• The lymph vessels from the
rest of penis drain into
superficial inguinal lymph
PRIMORDIAL GERM CELLS
• The primordial germ cells develop
from the wall of the yolk sac and
migrate towards the developing
• Spermatozoa develop from the
primordial germ cells.
DEVELOPMENT OF TESTIS
• Each testis develops from the
coelomic epithelium that covers
the medial side of the
mesonephros, of the corresponding
• The germinal epithelium becomes
thickened, this thickening is called
the genital ridge
• The cells of the germinal epithelium
proliferate and form a number of solid sex
cords that grow into the underlying
• They reach deep into the gonad and are
called medullary cords
• The medullary cords are soon canalized to
form the seminiferous tubules
• The mesenchymal cells, surrounding the
developing testis, form a dense layer of fibrous
tissue. This is the tunica albuginea
• It completely separates the sex cords from the
germinal epithelium and, thereafter, this
epithelium can make no further contribution to
• The mesonephric tubules that lie near the
testis along with the mesonephric duct form
the duct system of the testis
• The ends of the seminiferous tubules
anastomose with one another to form the
• The cranial part of the mesonephric duct
becomes highly coiled on itself to form the
epididymis while its distal part becomes the
• The testes develop in relation to the lumbar
region of the posterior abdominal wall.
During fetal life, they gradually descend to
• They reach the iliac fossa during the 3rd
month, and lie at the site of the deep
inguinal ring up to the 7th month of
• They pass through the inguinal canal during
the 7th month and are normally in the
scrotum by the end of the 8th month
• The testis presents the following external
features: Two poles—upper and lower. Two
borders—anterior and posterior. Two
surfaces—medial and lateral.
• The testis is suspended in the scrotum by
the spermatic cord.
• Numerous incomplete fibrous septa extend from the
mediastinum to the inner aspect of the tunica
albuginea and divide the interior of the testis into
• Each lobule contains two to four coiled seminiferous
tubules, lined by thick multilayered germinal
epithelium that produces spermatozoa
• The thin, thread-like loops of seminiferous tubules
join each other and become straighter as they pass
toward the mediastinum forming straight tubules.
• The straight seminiferous tubules do not produce
spermatozoa but discharge them into the network of
channels called the rete testis.
• The small efferent ductules connect the channels of
rete testis to the upper end of the epididymis.
• The testicular artery supplies the testis,
which arises from the abdominal aorta in
the abdomen at the level of L2 vertebra.
• It passes downward and laterally to enter
the deep inguinal ring, traverses through
the inguinal canal within the spermatic
cord to reach the testis.
• The pampiniform plexus of veins (the
veins emerging from the testis form a
plexus of veins called pampiniform
plexus) drains the venous blood from
• This plexus ascends up and at the
superficial inguinal ring condenses to
form four veins, which pass through
the inguinal canal within the spermatic
• At the level of deep inguinal ring,
they join to form a two testicular veins
The lymph vessels from
the testis ascend along
the testicular vessels in
the spermatic cord and
drain into pre-aortic and
para-aortic group of
lymph nodes at the level
of the second lumbar
• The functions of the testis include –
• production of spermatozoa and
• secretion of testosterone (or dihydrotestosterone)
• It is a cutaneous pouch consisting of thin
skin and the underlying dartos, which is
continuous with the superficial penile
fascia and superficial perineal fascia.
• The dartos muscle is responsible for
wrinkling the scrotal skin, and the
cremaster muscle is responsible for
elevating the testis.
• It has no fat, which is important in
maintaining a temperature lower than the
rest of the body for sperm production.
• Scrotum is divided into right and left
halves by a median ridge or raphe,
which indicates the line of fusion of
the two halves of the scrotum.
• The left half of the scrotum hangs
lower than the right half, because
the left spermatic cord is longer
than the right spermatic cord
The following arteries supply
1. Superficial external pudendal
2. Deep external pudendal
3. Scrotal branches of the
internal pudendal artery.
4. Cremasteric artery, a branch
of the inferior epigastric artery
1. Anterior one-third of the scrotum is
supplied by ilioinguinal nerve (L1)
and genital branch of genitofemoral
2. Posterior two-third of the scrotum
is supplied by posterior scrotal
branches of the perineal nerve (S3)
and perineal branch of the
posterior cutaneous nerve of the
3. The involuntary dartos muscle is
supplied by the sympathetic fibres
through genital branch of the
• The epididymis is a comma-shaped
structure, which lies on to the
superior and posterolateral surface
of the testis.
• It is made up of highly coiled tubes
• The epididymis from above downward
is divided into three parts:
Head, Body, and Tail
• The head (the upper expanded part) is
connected to the upper pole of testis
by efferent ductules
• The body (middle part) and tail (lower
period part) are made up of a single
highly coiled duct of epididymis,
which emerges from the tail as the
1. Storage and maturation of spermatozoa.
2. Absorption of the fluid.
3. Addition of substances to the seminal fluid to nourish the
• Is a diamond-shaped space
• Is bounded by –
pubic symphysis anteriorly,
the ischiopubic rami anterolaterally,
the ischial tuberosities laterally, the
the tip of the coccyx posteriorly.
• Perineum is divided into –
an anterior urogenital triangle
a posterior anal triangle
• by a line connecting the two
• Superficial Perineal Space (Pouch)
Lies between the inferior fascia of the
urogenital diaphragm (perineal membrane)
and the membranous layer of the superficial
perineal fascia (Colles’s fascia)
• Perineal Membrane
• Deep Perineal Space (Pouch)
Contains the deep transverse perineal muscle
and sphincter urethrae, the membranous part
of the urethra, the bulbourethral glands
The primitive urogenital sinus is divided into
cranial vesicouretheral sinus and
caudal definitive urogenital sinus
Gerotas fascia – T4 disease
The commonest site of rupture is bulb of the penis, just below the urogenital diaphragm following a fall astride a sharp object
The prostate is like an inverted cone in shape and resembles a chestnut in appearance
internal iliac veins → IVC. This pathway explains the metastasis of cancer prostate into the lungs.
vertebral venous plexus (of Batson) → intracranial dural venous sinuses. This pathway explains the metastasis of cancer prostate into the vertebral column and brain.
Hydrocele: It is the accumulation of the fluid within the tunica vaginalis.
Varicocele: It is a clinical condition in which veins of the pampiniform plexus become dilated, tortuous, and elongated
‘bag of worms’.
Contains the testis and its covering and the epididymis.
Scrotal edema: The scrotum is a common site of edema due to laxity of the skin and its dependent position.
Sebaceous cysts: These often occur in the scrotum due to the presence of a large number of hair and sebaceous glands in the scrotum.
Torsion of the testis: It is a clinical condition in which rotation of the scrotum occurs around the spermatic cord within the scrotum. It commonly affects the active young people and children, and is accompanied by severe pain.
Scrotal elephantiasis: It is a clinical condition characterized by a massive swelling and enlargement of the scrotum due to accumulation of interstitial fluid in the scrotal wall following blockage of lymph vessels by slender worms of filariasis (Wuchereria bancrofti).