Urogenital system development. Urinary bladder development. kidney Development.

1. Development of Urinary system
and
Suprarenal Gland
Dr.Deepak N.Khedekar.
Dept.of Anatomy
LTMMC &GH
2016

2. Introduction…
Uro-genital system is divided functionally into
➢Urinary system
➢Genital system.
• System includes all the organs involved in
reproduction and forming and voiding urine.
• Embryologically, the systems are closely
associated, especially during their early stages
of development.

3. Intermediate
mesoderm
Derived from
intraembryonic
mesoderm
Gives rise to
“Paired Glands”
➢Kidneys,
➢Adrenals
➢Gonads

4. Intra-embryonic Mesoderm
• Appears in the 3rdweek embryo
• Divided into 3 parts ....
➢Paraxial (near to notochord)= somites
➢Intermediate = Uro-genital system
➢Lateral plate = intraembryonic coelom

5. Derivates of Intra-embryonic Mesoderm

6. Intermediate Mesoderm
• During folding of the embryo in the horizontal
plane , this mesoderm is carried ventrally and
loses its connection with the somites.
• Dorsal side of intra-embryonic coelom, each
cord produces a bulge into the coelom called
the urogenital ridge
• Intermediate mesoderm - Urogenital ridge

7. Intra-embryonic Mesoderm

8. Urogenital ridge
• Longitudinal elevation of mesoderm along
the dorsal body wall.
• Forms on each side of the dorsal aorta
• Consist of ...
➢Nephrogenic cord - Part of the urogenital
ridge giving rise to the urinary system
➢Gonadal ridge - part giving rise to the
genital system.

9. Responsible genes
Genes is needed for the formation of the
urogenital ridge:
➢Wilms tumor suppressor 1 (WT1),
➢Steroidogenic factor 1, and DAX1 gene.

10. Formation of intermediate mesoderm

11. Nephrogenic cord
• Develops into three sets of nephric or
kidney structures:
➢Pronephros - analogous to kidneys in
primitive fishes
➢Mesonephros - analogous to kidneys
in amphibians
➢Metanephros - become permanent
kidneys

12. Nephrogenic cord

13. Pronephros
• Cranial-most nephric structure represented by a few
cell clusters and tubular structures
• Form pronephric tubules and pronephric duct.
• Pronephric ducts run caudally and open into the
cloaca.
• Transitory structure that appears on 21st day and
regresses completely by week 5th or on 24th day.
(Not functional in humans.)
• Most parts of the pronephric ducts persist and are
used by the next set of kidneys i.e mesonephros.

15. Mesonephros
• Middle nephric structure
• Partially transitory structure.
• First appears early in week 4th .
• Form mesonephric tubules and the
mesonephric duct (Wolffian duct).
• Develops in thoracic and lumbar segments of
intermediate mesoderm.
• Most of the mesonephric tubules regress, but
the mesonephric duct persists and opens into
the urogenital sinus.

16. Mesonephros
• Urine is produced and
drains along the
mesonephric (Wolfian)
duct to the
cloaca/bladder.
• In week 5th ,thoracic
segments regress but the
mesonephric kidney
continues functioning
until week 10.
• Functional for a short
period.

17. Nephrogenic cord

18. Metanephros / Metanephroi
Primordia of permanent kidneys
• Caudal-most nephric
structure.
• Develops from an outgrowth
of the mesonephric duct
(Ureteric bud)
• From a condensation of
mesoderm within the
nephrogenic cord called the
metanephric mesoderm.

19. Metanephros / Metanephroi - Primordia
of permanent kidneys
• Begins to form at week 5
• Functional in the fetus at
about week 10.
• Urine is excreted into the
amniotic cavity and mixes
with the amniotic fluid.
• Fetal kidney is divided into
lobes, in contrast to the
definitive adult kidney,
which has a smooth contour

20. Development of Kidney
Permanent kidney:
Develop from two sources…
➢Ureteric bud (metanephric
diverticulum near its
entrance into the cloaca)
➢Metanephrogenic
blastema (metanephric
mass of mesenchyme)

21. Development of the collecting system
Ureteric bud:
➢Initially penetrates
the metanephric
mesoderm
Undergoes repeated
branching to form…
➢ Ureters
➢ Renal pelvis,
➢ Major calyces,
➢ Minor calyces,
➢ Collecting ducts.

22. Ureteric bud
Outgrowth is regulated by…
➢WT-1 (an anti-oncogene)
➢GDNF (glial cell line-derived neurotrophic
factor)
➢ c-Ret (a tyrosine kinase receptor).

24. Collecting system
• Stalk of the ureteric bud - Ureter.
• Cranial part of the bud undergoes repetitive branching,
forming branches which differentiate into the-
collecting tubules of the metanephros .
• first four generations - form the major calices .6wk
• Second four generations -form the minor calices.7wk
• End of each arched collecting tubule induces clusters of
mesenchymal cells in the metanephrogenic blastema to
form small metanephric vesicles .
• Metanephric Vesicles elongate – Metanephric Tubules

25. Ureteric bud
Metanephrogenic blastema is derived from the
caudal part of the nephrogenic cord

26. Nephron development

27. S-shaped Metanephric tubules or
renal tubules
Differentiate into the…
➢Collecting tubule,
➢Distal convoluted
tubule,
➢Loop of Henle,
➢Proximal convoluted
tubule
➢Bowman capsule

29. Nephron development
• Tufts of capillaries called glomeruli protrude
into Bowman capsule.
• Nephron formation is complete at birth,
• Functional maturation of nephrons continues
throughout infancy.

30. Uriniferous tubule
• Consists of two
embryologically
different parts…
➢Nephron - derived from
the metanephrogenic
blastema
➢Collecting tubule -
derived from the
ureteric bud

31. Tissue sources
• Lining epithelium derived from mesoderm of the
ureteric bud:
➢1.Transitional epithelium lining the ureter, pelvis,
major calyx, and minor calyx and the
➢2.Simple Cuboidal epithelium lining the collecting
tubules.

33. Tissue sources
• Lining epithelium derived from Metanephric
Mesoderm
➢1.Simple cuboidal epithelium lining the collecting
tubule and distal convoluted tubule
➢2.Simple squamous epithelium lining the loop of
Henle,
➢3.Simple columnar epithelium lining the proximal
convoluted tubule, and the podocytes
➢4.Simple squamous epithelium lining Bowman’s
capsule.

34. Nephron Formation
• Between the 10th and 18th weeks,
• Number of glomeruli increases gradually
• Rapid increase observed till the 32nd week,
when an upper limit is reached.
At term, nephron formation is complete
Each kidney containing as many as 2 million
nephrons.

35. Positional Changes of Kidneys
• Initially the primordial permanent kidneys lie close
to each other in the pelvis, ventral to the sacrum.
• As the abdomen and pelvis grow, the kidneys
gradually relocate to the abdomen and move
farther Apart .
• Attain their adult position by the 9th week .
• “Ascent” results mainly from the growth of the
embryo’s body caudal to the kidneys.
• Caudal part of the embryo grows away from the
kidneys so that they progressively occupy their
normal position on either side of the vertebral
column.

36. Positional Changes of Kidneys
• Initially the hilum of each kidney, face
ventrally;
• As the kidneys relocate (“ascend”), they
rotate medially almost 90 degrees.
• By the 9th week, the hila are directed
anteromedially .
• Eventually the kidneys become retro-
peritoneal on the posterior abdominal wall.

37. Positional Changes of Kidneys

38. CLOACA

40. Development of Urinary Bladder
Urogenital sinus is divided into three parts :
• Vesical part - forms most of the urinary
bladder and is continuous with the allantois.
• A pelvic part -becomes the urethra in the
neck of the bladder, the prostatic part of the
urethra in males, and the entire urethra in
females
• A phallic part -grows toward the genital
tubercle (primordium of the penis or clitoris)

42. Development of Urinary Bladder
• Urinary bladder develops mainly from the
vesical part of the urogenital sinus,
• Trigone is derived from the caudal ends of
the mesonephric ducts .
• Entire epithelium of the bladder is derived
from the endoderm of the vesical part of the
urogenital sinus.
• Other layers of its wall develop from adjacent
splanchnic mesenchyme.

43. Development of Urinary Bladder

44. Development of Urinary Bladder

45. THANK YOU

46. Development of suprarenal gland
• Cortex develops from mesenchyme.
• Medulla from neural crest cells.
• During the 6th week, the cortex begins as an
aggregation of mesenchymal cells on each
side of the embryo between the root of the
dorsal mesentery and the developing gonad.
• Cells that form the medulla are derived from
an adjacent sympathetic ganglion, which is
derived from neural crest cells.

47. Development of suprarenal gland
• Neural crest cells form a mass on the medial
side of the embryonic cortex.
• As they are surrounded by the cortex, the cells
differentiate into the secretory cells of the
suprarenal medulla.
• More mesenchymal cells arise from the
mesothelium and enclose the cortex.
• Cells give rise to the permanent cortex of the
suprarenal gland .

48. Development of suprarenal gland
• Immuno histo-chemical studies identify a
“transitional Zone”that is located between the
permanent cortex and the fetal cortex.
• Zona fasciculata is derived from this third
layer.
• Zona glomerulosa and Zona fasciculata are
present at birth.
• Zona reticularis is not recognizable until the
end of the third year.

49. Development of suprarenal gland

50. Development of suprarenal gland
• Relative to body weight, the glands of the fetus are
10 to 20 times larger than in the adult and are large
compared with the kidneys .
• These large glands result from the extensive size of
the fetal cortex, which produces steroid precursors
that are used by the placenta for the synthesis of
estrogen.

51. Development of suprarenal gland
• Medulla remains relatively small until after
birth. The glands rapidly become smaller as
the fetal cortex regresses during the first year
of infancy
• Glands lose approximately one third of their
weight during the first 2 or 3 weeks after birth
and do not regain their original weight until
the end of the second year.

52. Thank you