Development of kidney & its anomalies

DEVELOPMENT OF
KIDNEYS AND ITS
ANAMOLIES
1

• "It is not birth,
marriage, or death,
but gastrulation
which is truly the
most important time
in your life."
– Prof Lewis Wolpert
2

• Gastrulation begins between days
14 and 16 of human
development.
• Gastrulation results in formation
of the 3 germ layers:
• Mesoderm(e.g. muscle, bone,
kidneys)
• Endoderm (e.g. gut) and
• Ectoderm (e.g. nervous
system/epidermis)
3
Zygote
Blastocyst
Three germ layers:
1) Mesoderm
2) Endoderm
3) Ectoderm

INTRODUCTION
• The embryonic structures that play an important role in
development of GUS are:
1. Intermediate Mesoderm
2. Cloaca
4

INTERMEDIATE MESODERM
Intra-embryonic mesoderm is
subdivided into
• Paraxial mesoderm
• Intermediate mesoderm
• Lateral mesoderm
5

Kidney Development
 After the folding of the embryonic disc, the intermediate mesoderm
forms a bulging on the posterior abdominal wall, called the
NEPHROGENIC CORD/ UROGENITAL RIDGE
 It extends from the cervical region to the sacral region of the
embryo.
UROGENITAL
RIDGE

CLOACA
• Primitive urogenital sinus
1) Vesico-urethral canal
2) Definative urogenital sinus
- Pelvic part
- Phallic part
9

DEVELOPMENT OF KIDNEYS
• The kidneys develop originally as a pair
of structures located in the cervical and
thoracic region of the developing
embryo.
• They develop from intermediate
mesoderm.
10

• The Human Kidney
develops in 3 successive
stages (rostral to caudal)
 PRONEPHROS
 MESONEPHROS
 METANEPHROS
 They are aligned adjacent to
the Wolffian / Nephric Duct
11

Development of Kidney
• PRONEPHROS
– First to form, appears in the cervical region .
• MESONEPHROS
– Second to form, consist of a series of excretory
tubules that develop in the thoracolumbar
region.
• METANEPHROS
– Final formation, in the sacral region

Ontogeny recapitulates phylogeny
13

Ernst Haeckel 1860
• Ontogeny is the development of the
individual
• Phylogeny is the evolution of the species
• So this is the idea that during
development an organism (or an organ)
goes through the same stages as during
their evolution.
• Consider the Frog
– It development retraces the
evolution of vertebrates from fish to
reptiles
– From the tadpole stage
• Water breathing with tail and no
limbs (like a fish)
• Rudimentary limbs
• Reduction of tail
• Development of lungs –
breathes air
• Fully developed limbs, loss of tail
moves onto land
– To the fully developed frog
14

Pronephros
 The PRONEPHROS
develops from the cranial
most part of urogenital
ridge.
 It is transitory, non
functional and regresses
completely by 5 weeks of
gestation.
 Analogous to primitive
fish.

• The human pronephros are
never functional and
degenerates on 24th or 25th
day.
• A nephric duct is formed in
relation to the pronephros
and ends into cloaca
however persists.
• 7-10 solid or tubular
arranged cell groups in
the cervical region (head
kidney)
17

Pronephric
tubule
Pronephros
Time：3rd week
Function：no
Destiny: degeneration in
the 5th week

Mesonephros
 MESONEPHROS develops
caudal to the Pronephros in
thoracolumbar region.
 It consists of a series of
tubules that drain into the
nephric duct, which can be
called the Mesonephric duct.
 Transistionary Excretory
organ for embryo until
metanephros takes over.

• The blind end of the duct grows towards
the primitive cloaca and soon fuses to it
about 28th day.
 By the 4th month of gestation-completely
disappears.
 Before its degeneration some of its cells
migrate and ultimately form the
• Adrenal glands
• Gonads
20

Time：
end of 4th week
Function:
transient urinary
Destiny:
Most degeneration,
Small part form male
excurrent duct
Mesonephric duct
Mesonephric tubule

 METANEPHROS, third
and final stage of Kidney
development
 It results from Reciprocal
inductive signals between
the Metanephric
Mesenchyme (MM) and the
Ureteric Bud (UB) at the
caudal end of the
Urogenital bridge.
 Ureteric bud is an
outgrowth at the distal end
of the Wolfian duct, first
visible at approx. 5 weeks
of gestation.
Metanephros

Time：begin at 5th week,
exist forever
Function：begin at 3th month,
urinary function
Position：rise gradually
Metanephros
Metanephros

Kidney
Development
Development
of the
NEPHRON
Development
of the
COLLECTING
SYSTEM Development
of the
VASCULATURE

Development of Nephron
Upon invasion of UB in the
loose MM, signals from MM
cause UB to branch into a T -
tubule
Signals from UB induce the
MM to condense along the
surface of UB
The METANEPHRIC
MESENCHYME (MM)
becomes distinct from the
surrounding loose
mesenchymal cells and come
to lie adjacent to the
URETERIC BUD (UB).

 After condensation a subset of the MM
aggregates inferior and adjacent to the
tips of the branching ureterIc bud,
forming the PERITUBULAR
AGREGATES.
 These undergo mesenchyme – to –
epithelial transformation and form the
RENAL VESICLE
 The Renal vesicle ultimately forms the
• Glomerulus
• Proximal Convoluted tubule
• Loop of Henle
• Distal Convoluted tubule
Renal
Vesicle

Renal Vesicle in contact with the
epithelium of the ureteric bud forms
the ‘COMMA SHAPE’
Glomerulus develops from the most
proximal end of the Renal Vesicle,
farthest from UB tip.
These cells develop into Podocytes.
Vascular cleft develops between
podocyte layes and the more
proximal cells – ‘S SHAPE’
Endothelial cells migrate into the
vascular cleft
Mesangial cell ingrowth follows the
endothelial cells into the vascular
cleft.

Development of kidney & its anomalies

• In principle, all nephrons are formed in the same way and can
be classified into fairly well-defined developmental stages
(Larsson et al, 1983).
- Stage I
- Stage II
- Stage III
- Stage IV
30

Development of the Collecting
System
 The collecting ducts are all derived from the Ureteric Bud.
 The ureteric bud initially penetrates the metanephric mesoderm to form an ampulla,
and then undergoes repeated branching to form the ureters, renal pelvis, major calyces,
minor calyces, and collecting ducts.
 This branching is highly patterned

• By the 6th week, the ureteric bud
has bifurcated at least four times,
yielding approximately 16
branches.
• These branches then coalesce to
form two to four major calyces
extending from the renal pelvis.
• By the 7th week, the next four
generations of branches also
fuse, forming the minor calyces.
• By the 32nd week, approximately
11 additional generations of
bifurcation have resulted in
approximately 1 million to 3
million branches, which become
the collecting duct tubules
32

After the first few rounds of branching of the UB derivatives and
the concomitant induction of nephrons, the kidney begins to
become divided into an outer CORTICAL region (where
nephrons are being induced) and an inner MEDULLARY region
where the collecting system forms.
As growth continues successive groups of nephrons are induced
at the peripheral regions of the kidney, known as the
NEPHROGENIC ZONE.

Schematic representation of progressive
nephron
differentiation.
• Older, more
differentiated nephrons
are located in the inner
part of the kidney near
the juxtamedullary
region.
• Newer, less
differentiated nephrons
are found at the
periphery.
34

Development of Vasculature
• Angiogenic Hypothesis- derived
from branches off aorta and
other pre-existing extrarenal
vessels.
• Vasculogenic Hypothesis-
originate in situ from vascular
progenitor cells (VEGF).

Ascent of Kidneys
• During the fifth and sixth weeks of development, the mature
kidneys lie in the pelvis with their hila pointed anteriorly.
• As the pelvis and abdomen grow, the kidneys slowly move
upward.
• By the seventh week, the hilum points medially and the
kidneys are located in the abdomen.
• As the embryo continues to grow in a caudal direction, the
kidneys are left behind and eventually come to lie in a
retroperitoneal position at the level of L1 by the ninth week
of development.
• In the meantime, the kidneys have completed rotation and
the hila now face anteromedially.

• The metanephric ducts elongate and become the
ureters.
• As the kidney ascends it receives new segmental
arteries from the aorta and loses those vessels
below (“climbing a ladder”). Thus sometimes
there is more than one renal artery.
• Sometimes one kidney fails to ascend => pelvic
kidney
• Sometimes the left and right kidneys become
attached in the pelvis then the horseshoe kidney
can’t ascend above the inferior mesenteric artery
37

Molecular mechanism of ureteral bud outgrowth
GDNF-(glial cell line- derived neurotrophic factor) ret Signaling in Kidney Development
Ret is a tyrosine kinase receptor
Ret is expressed in the Wolfian duct and the ureteric bud.
For stimulation of ureteric bud branching
By the time the bud has branched several times, expression is restricted to the tips of the
branches.

• In particular, several lines of
experimental evidence have revealed
a crucial role of the RET-GDNF-GFRα1
pathway in ureteric bud outgrowth.
41

Timeline of Kidney Embryology
• Week 4 : appearance of Wolffian or
Mesonephric Duct
• Day 28 : formation of Ureteric Bud (UB)
• Week 4-8 : Initial MM induction and UB
branching
• Week 8 : First nephrons are formed
• Week 6-8 : kidneys ascend from pelvis to
lumbar location
• Week 8-15 : Period of UB branching with
stochastic formation of UB ampulla and nephron units
• Week 10 : filtration begins
• Week 32-36: End of Nephrogenesis

CONGENITAL ANOMALIES
1. Anomalies of number
2. Anomalies of ascent
3. Anomalies of form and fusion
4. Anomalies of rotation
5. Anomalies of the collecting system
6. Anomalies of renal vasculature
43

ANOMALIES OF NUMBER
1. Bilateral renal agenesis (BRA) -
• First recognized 1671 by Wolfstrigel.
• Quite rare.
• 500 cases have been cited in the literature.
• Significant Males predominance.
• Increase maternal age.
44

 Cause : The absence of a nephrogenic ridge on the
dorsolateral aspect of the coelomic cavity or the failure of a
ureteral bud to develop from the mesonephric duct will lead
to agenesis of the kidney.
• Besides the absence of functioning kidneys, each ureter may
be either wholly or partially absent.
• Complete ureteral atresia is observed in 50%.
46

• 40% of the affected infants are stillborn.
• Most of the children who are born alive do not survive
beyond 48 hours because of respiratory distress associated
with pulmonary hypoplasia.
47

 Associated anomalies seen are
1. Low birth weight – 1000-2000 g.
2. IUGR.
3. Potters facial appearance.
4. Legs often bowed and clubbed.
5. Skin excessively dry.
6. Hands are relatively large and clawlike.
49

7. Pulmonary hypoplasia - anephric fetus fails to produce proline,
which is needed for collagen formation in the bronchiolar
tree.
8. In males, rarely hypospadias and undescended testis.
9. In females, ovaries are hypoplastic or absent. Uterus is usually
rudementary or bicornuate with vagina short, blind or
completely absent.
50

• Diagnosis – characteristic potter facies, presence of
oligohydraminos and presence of amnion nodusum - small
white, keratinized nodules found on the surface of the
amniotic sac—may also suggest this anomaly.
• Anuria after the first 24 hours without distention of the
bladder should suggest renal agenesis.
51

• Renal ultrasonography is probably the easiest way to identify
the kidneys and bladder to confirm the presence or absence
of urine within these structures.
• Doppler ultrasonography to diagnose renal agenesis when
renal arteries are not detectable has been highly accurate,
even in fetuses with oligohydramnios.
52

2. Unilateral renal agenesis (URA) –
• More commonly than BRA.
• Occurs once in 1100 births.
• Males predominant 8:1.
• More frequently on left side.
53

 Cause :
• Fault lies most probably with the ureteral bud.
• Complete absence of a bud or aborted ureteral development
prevents maturation of the metanephric blastema into adult
kidney tissue.
• It is unlikely that the metanephros is responsible, because the
ipsilateral gonad is rarely absent, malpositioned, or
nonfunctioning.
• Occurs no later than 4th or 5th week of gestation.
54

• Magee and coworkers (1979) proposed an embryologic
classification based on the timing of the faulty differentiation-
• Type I – before 4th week.
unilateral agenesis of GUS.
55

• Type II – early 4th week.
- affects both mesonephric duct
and ureteral buds.
- didelphys uterus with obstructive
ipsilateral horn and vagina.
• Type III – after 4th week.
- mesonephric duct devlops
normally only ureteral bud or
metanephric blastema affected.
56

 Associated anomalies –
1. The ipsilateral ureter is completely absent in slightly more
than half of the patients.
2. Ipsilateral adrenal agenesis -rare
3. Genital anomalies are much more frequently observed.
Despite the predominance in males(10% to 15%),
reproductive organ abnormalities seem to occur more in
females (25% to 50%).
57

• The diagnosis should be suspected during a physical
examination when the vas deferens or body and tail of the
epididymis is missing or when an absent, septate, or
hypoplastic vagina is associated with a unicornuate or
bicornuate uterus.
• Cystoscopy - reveals an asymmetrical trigone
either partial or complete ureteral atresia
58

3. Supernumerary kidney –
• Is truly an accessory organ
with its own collecting
system, blood supply, and
encapsulated parenchymal
mass.
• Only 100 cases reported.
• Left side.
• Affects equally men and
women.
60

 Cause :
• The sequence of interdependent events involved in ureteral
bud formation and metanephric blastema development,
which is required for the maturation of the normal kidney,
probably also allows for the occurrence of a supernumerary
kidney.
• It is postulated that a deviation involving both of these
processes must take place to create the anomaly.
61

• A second ureteral outpouching off the wolffian duct or a
branching from the initial ureteral bud appears as a necessary
first step.
• Next, the nephrogenic anlage may divide into two
metanephric tails, which separate entirely when induced to
differentiate by the separate or bifid ureteral buds.
• The twin metanephros develop only when the bifid or
separate ureteral buds enter them.
62

• The supernumerary kidney is a distinct parenchymatous mass
that may be either completely separate or only loosely
attached to the major kidney on the ipsilateral side.
• In general, it is located somewhat caudal to the dominant
kidney, which is in its correct position in the renal fossa.
• Occasionally, the supernumerary kidney lies either posterior
or craniad to the main kidney, or it may even be a midline
structure anterior to the great vessels and loosely attached to
each of the other two kidneys
63

• A to H, Various patterns
of urinary drainage when
ureters form a common
stem.
• All kidney positions are
relative only and are
depicted on the left side
for ease of interpretation.
• Dashed lines indicate that
detail was not defined
64

• The ureteral interrelationships on the side of the
supernumerary kidney are quite variable.
• Convergence of the ipsilateral ureters distally to form a
common stem and a single ureteral orifice occurs in 50% of
the cases.
• Two completely independent ureters, each with its own
entrance into the bladder, are seen in the other 50% of cases.
65

• It may not produce symptoms until early adulthood.
• Average age at diagnosis 30 to 36 years.
• A supernumerary kidney may become symptomatic from
hydronephrosis or even stone formation.
• Cystoscopy reveals one or two ureteral orifices on the
ipsilateral side.
66

ANOMALIES OF ASCENT
1. Simple renal ectopic –
• Fails to reach its normal location in renal fossa.
• Found in – pelvis, iliac, abdomen, thorax and crossed.
• 1 in 900.
• Left side is more common.
67

• The classification of ectopia is
based on the position of the
kidney within the
retroperitoneum:
• the pelvic kidney is opposite the
sacrum and below the aortic
bifurcation;
• the lumbar kidney rests near the
sacral promontory in the iliac
fossa and anterior to the iliac
vessels;
• the abdominal kidney is so
named when it is above the iliac
crest and adjacent to the second
lumbar vertebra.
68

• Factors that may prevent the orderly movement of kidneys
include
- ureteral bud maldevelopment,
- defective metanephric tissue that by itself fails to induce
ascent,
- genetic abnormalities, and
- maternal illnesses or teratogenic causes.
• Genital anomalies are more commonly associated with it.
69

• The renal pelvis is usually anterior because the kidney has
incompletely rotated.
• As a result, 56% of ectopic kidneys have a hydronephrotic
collecting system.
• Half of these cases result from obstruction at either the
ureteropelvic or the ureterovesical junction (70% and 30%,
respectively); 25% from reflux grade 3.
70

 Associated anomalies :
• In females - bicornuate or unicornuate uterus with atresia of
one horn, rudimentary or absent uterus and proximal and/or
distal vagina.
• In males - undescended testes, duplication of the urethra, and
hypospadias.
• Rarely adrenal glands are absent or abnormally positioned.
71

• Clinically asymptomatic.
• Vague abdominal complaints or frank ureteral colic secondary
to obstructing stone is the most frequent symptoms leading
to discovery of the misplaced kidney.
• The abnormal position of the kidney results in a pattern of
direct and referred pain that is atypical for colic and may be
misdiagnosed as acute appendicitis or as pelvic organ
inflammatory disease in female patients.
72

2. Thoracic kidney –
• partial or a complete protrusion of the kidney above the level
of the diaphragm into the posterior mediastinum.
• 200 cases have been reported.
• The renal counter and collecting system are usually normal.
73

 Cause :
• Kidney reaches to its normal location by end of 8th week.
• Delayed closure of diaphramatic anlage which allows renal
ascent above the level of future diaphragm or
• The kidney overshoot because of accelerated renal ascent
before diaphragmatic closure.
75

• Associated anomalies : elongated ureter.
• Majority are asymptomatic.
• Diagnosis is most commonly made after a routine chest
radiograph in which the affected hemidiaphragm is found to
be elevated slightly.
76

3. Cephalad renal ectopia –
• Kidney is positioned more cranially than normal.
• H/o – Omphalocele.
• When liver herniates into omphalocele sac with the intesitine
the kidney continues to ascend till they are stopped by
diaphragm at 10th thoracic vertebra.
• Ureter are excessively long.
77

Anomalies of form and fusion
1. Crossed renal ectopia with or without fusion –
• When a kidney is located on the side opposite from which its
ureter inserts into the bladder, the condition is known as
crossed ectopia.
• Ninety percent of crossed ectopic kidneys are fused.
78

• McDonald and McClellen classified :
79

Six forms of crossed renal
ectopia with fusion.
80

• First reported in 1654.
• 62 patients with crossed ectopia without fusion been
reported.
• Solitary crossed ectopia has been reported in 34 patients.
• Crossed ectopic with fusion seen in 1 in 1000 live birth.
• Unilaterally fused kidney with inferior ectopia is the most
common variety, whereas fusion with superior ectopia is the
least common.
81

 Cause :
• The reason of crossed ectopia are uncertain.
• Wilmer (1938) suggested that crossover occurs as a result of
pressure from abnormally placed umbilical arteries that
prevent cephalad migration of the renal unit, which then
follows the path of least resistance to the opposite side.
82

• Potter (1952) and Alexander and coworkers (1950) theorized
that crossed ectopia is strictly a ureteral phenomenon, with
the developing ureteral bud wandering to the opposite side
and inducing differentiation of the contralateral nephrogenic
anlage.
• Fusion of the metanephric masses may occur when the renal
anlagen are still in the true pelvis before or at the start of
cephalad migration, or it may occur during the latter stages of
ascent.
83

• It is the superior pole of the ectopic kidney that usually joins
with the inferior aspect of the normal kidney.
• Ascent continues until either the uncrossed kidney reaches its
normal location or one of the retroperitoneal structures
prevents further migration of the fused mass.
• The final shape of the fused kidneys depends on the time and
extent of fusion and the degree of renal rotation that has
occurred.
84

• When the kidney not fused, the uncrossed kidney usually
resides in its normal dorsolumbar location while the ectopic
kidney is inferior and in either a diagonal or a horizontal
position with an anteriorly placed renal pelvis.
• Solitary crossed ectopia, the kidney is usually located
somewhat low but in the opposite renal fossa at the level of
L1-L3 and is oriented anteriorly, having incompletely rotated
on its vertical axis
85

 Associated anomalies :
• In all the types of fusion anomalies, the ureter from each
kidney usually is not ectopic. Except for solitary crossed
ectopia, in which there may be a hemitrigone or a poorly
developed trigone with a rudimentary or absent ureter on the
side of the ectopic kidney.
• Vesicoureteral reflux is noted in 20% of crossed ectopia.
86

• The highest incidence of associated anomalies occurs in
children with solitary renal ectopia and involves both the
skeletal system and genital organs.
• Males - cryptorchidism or absence of the vas deferens;
• Female - vaginal atresia or a unilateral uterine abnormality.
• Imperforate anus has also been observed in 20% of the
patients.
87

• As crossed ectopic anomalies have no symptoms. The defects
are often discovered incidentally at autopsy, during routine
perinatal ultrasound screening, or after bone scanning.
• Cystoscopy and retrograde pyelography were useful in
mapping out the collecting system and pattern of drainage.
88

2. Horseshoe Kidney –
• Most common of all renal fusion anomalies.
• The anomaly consists of two distinct renal masses lying
vertically on either side of the midline and connected at their
respective lower poles by a parenchymatous or fibrous
isthmus that crosses the midplane of the body.
• 1 in 500 births.
• 7% seen in Turners syndrome baby.
• 2 to 8 times more likely to have wilms tumor.
89

• The abnormality occurs between the 4th and 6th week of
gestation.
• The intermediate mesoderm that gives rise to
the metanephric blastema fails to separate.
• As the ureteric bud grows cranially, they come into contact
with the fused nephrogenic cords and nephrogenesis
proceeds.
• With growth of the embryo, the ascent of the kidney is
arrested as the isthmus of the kidney makes contact with the
inferior mesenteric artery.
91

• Normal posterior rotation of the kidney is prevented by the
fusion resulting in the renal pelves becoming
orientated anteriorly.
• Fusion usually occurs at the lower poles. Upper
and midpole fusion is rare.
92

• Two theories of embryogenesis have been proposed –
- The classic theory involves mechanical fusion of two kidneys
during organogenesis. The inferior poles of kidneys touch and
fuse in the lower midline during the migration through the
narrow fork of umbilical arteries.
- An alternative theory proposes that there is abnormal
migration of posterior nephrogenic cells, which then coalesce
to form the parenchymal isthmus.
93

• In 95% of patients, the kidneys join at the lower pole; in a
small number, an isthmus connects both upper poles instead.
• Generally, the isthmus is bulky and consists of
parenchymatous tissue with its own blood supply.
• The horseshoe kidney even though it produces no symptoms,
is frequently found in association with other congenital
anomalies like :
94

1. vesicoureteral reflux (50%),
2. duplication of ureters (10%),
3. hypospadias
4. undescended testis (4%),
5. bicornuate or septate uterus (7%).
6. Horseshoe kidney is also frequently found in association with
other congenital anomalies. Most commonly affected organs
are cardiovascular, skeletal, and central nervous systems.
95

• 50% of patients are asymptomatic.
• In most the anomaly is incidental finding at autopsy.
• When symptoms are present they are related to
hydronephrosis, infection or calculus formation with vague
abdominal pain.
• Sometimes abdominal lump.
• Ultrasonography is detected.
96

ANOMALIES OF ROTATION
• The kidney, as it assumes its final position in the “renal” fossa,
orients itself so that the calyces point laterally and the pelvis
faces medially. When this alignment is not exact, the
condition is known as malrotation.
• Most often, is found with another renal anomaly, such as
ectopia with or without fusion or horseshoe kidney.
• It is frequently observed in patients with Turner's syndrome.
97

• Medial rotation of the collecting system occurs
simultaneously with renal migration.
• The kidney starts to turn during the 6th week, just when it is
leaving the true pelvis, and it completes this process, having
rotated 90 degrees toward the midline, by the time ascent is
complete, at the end of the 9th week of gestation
98

• That rotation is actually the result of unequal branching of
successive orders of the budding ureteral tree, with two
branches extending ventrally and one dorsally during each
generation or division.
• More parenchyma develops ventrally than dorsally, and the
pelvis seems to rotate medially.
99

• Rotation of the kidney during its
ascent from the pelvis. The left
kidney with its renal artery and the
aorta are viewed in transverse
section to show normal and
abnormal rotation during its ascent
to the adult site.
• A, Primitive embryonic position; hilus
faces ventrad (anterior).
• B, Normal adult position; hilus faces
mediad.
• C, Incomplete rotation.
• D, Hyperrotation; hilus faces dorsad
(posterior).
• E, Hyper-rotation; hilus faces laterad.
• F, Reverse rotation; hilus faces
laterad.
100

• Rotational anomalies do not produce any symptoms, but if
excessive rotation takes place can cause obstruction to
outflow leading to hydronephrosis.
• The diagnosis may be done when a renal calculus is detected
in an abnormal location, but confirmation should be obtained
only from a renal ultrasound, excretory urogram, or
retrograde pyelogram.
101

ANOMALIES OF THE COLLECTING
SYSTEM
1. Megacalycosis –
• Defined as nonobstructive enlargement of calyces resulting
from malformation of the renal papillae.
• It was first described by Puigvert in 1963.
• Most likely congenital and diagnosed prenatally.
• Males in a ratio of 6:1 and has been found only in white
patients.
• Bilateral disease has been seen almost exclusively in males,
whereas segmental unilateral involvement occurs only in
females.
102

• The calyces are generally dilated and malformed and may be
increased in number.
• The renal pelvis is not dilated, nor is its wall thickened, and
the UPJ is normally funneled without evidence of
obstruction.
• The cortical tissue around the abnormal calyx is normal in
thickness.
103

 Cause :
• There is transient delay in the recanalization of the upper
ureter after the branches of the ureteral bud hook up with the
metanephric blastema.
• This produces a short-lived episode of obstruction when the
embryonic glomeruli start producing urine.
• The fetal calyces may dilate and then retain their obstructed
appearance.
104

2. Extrarenal calyces –
• Congenital anomaly in which the major calyces as well as the
renal pelvis are outside the parenchyma of the kidney.
• Extrarenal calyces usually do not produce symptoms, although
failure of normal drainage may lead to stasis, infection, and
calculi.
106

ANOMALIES OF RENAL VASCULATURE
 Aberrant, Accessory, or Multiple Vessels
• Multiple renal arteries is the correct term to describe any
kidney supplied by more than one vessel.
• The term aberrant vessels should be reserved for those
arteries that originate from vessels other than the aorta or
main renal artery.
• The term accessory vessels denotes two or more arterial
branches supplying the same renal segment.
108

Accessory renal artey Multiple renal arteries
109

• The renal arterial tree is derived from three groups of
primitive vascular channels-
• The cranial group consists of two pairs of arteries dorsal to the
suprarenal gland that shift dorsally to form the phrenic artery.
• The middle group is made up of three pairs of vessels that
pass through the suprarenal area. They retain the same lateral
position and become the adrenal artery.
• The caudal group has four pairs of arteries that cross ventral
to the suprarenal area and become the main renal artery.
110

• The kidney may receive its blood supply partially or entirely
from arteries arising at an abnormal level.
• In the case of non ascent or of incomplete ascent the aberrant
arteries may constitute the only supply.
• It may press upon the ureter and cause obstruction leading to
hydronephrosis.
111

 Renal artery aneurysm
• The overall incidence has been calculated to be between 0.1%
and 0.3%.
• Most renal artery aneurysms are silent, especially in children.
• The diagnosis may be suspected with a pulsatile mass in the
region of the renal hilum or when an abdominal bruit is
heard.
112

• A wreathlike calcification in the area of the renal artery or its
branches (30%) is highly suggestive.
• Many asymptomatic renal artery aneurysms come to light
after the discovery and workup of hypertension.
114

Thank you
• “Now an embryo may seem
like some scientific or
laboratory term, but in fact
the embryo contains the
unique information that
defines a person. All you
add is food and climate
control, and some time, and
the embryo becomes you or
me.”
-
Todd Akin
115

Development of kidney & its anomalies

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