DEVELOPMENT OF URINARY BLADDER

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• FATE OF CLOACA
• Uro-rectal septum divides the endodermal cloaca
  into ventral primitive urogenital sinus and
  dorsal ano-rectal canal.
• Primitive uro-genital sinus receives the openings
  of 3 ducts 2 mesonephric ducts and allantois.
• A constriction at the level of enterance of
  mesonephric ducts divides the sinus into 2 parts
• Cranial vesico-urethral canal.
• Caudal defenitive uro-genital sinus.

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DEVELOPMENT OF URINARY BLADDER

• It develops from 3 parts
• Vesico-urethral canal (endodermal) forms most of
  the bladder.
• Proximal part of allantois (endodermal) forms
  apex of the bladder, rest of allantois is called
  urachus. Later the urachus becomes obliterated to
  be median umbilical ligament.
• Caudal parts of both mesonephric ducts forms the
  trigone of the bladder.

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CONGENITAL ANAMALIES

• Ectopia Vesicae due to failure of formation of
  anterior abdominal wall and anterior wall of
  urinary bladder.
• Urachal Fistula due to failure of obliteration
  of urachus.
• Urachal Cyst failure of obliteration of
  localized part of urachus.
• Urachal Sinus failure of obliteration of distal
  part of urachus.

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DEVELOPMENT OF MALE AND FEMALE URETHERA

• Female Urethra is developed mostly from
  vesico-urethral canal (cranial part of primitive
  uro-genital sinus).
• Male Urethera Is composed of 3 parts
• Prostatic urethera is developed from
  vesico-uretheral canal and absorbed mesonephric
  duct (upper 1/2) as well as pelvic part of
  defenitive uro-genital sinus (lower 1/2). 15 buds
  from the wall of urethera form the prostate gland
  by 12th week.
• Membranous urethera from pelvic part of
  defenitive uro-genital sinus.
• Penile urethera most of penile urethera is
  developed from phallic part of defenitive
  uro-genital sinus by the formation of uretheral
  plate then canal. Part of penile urethera in
  galns penis is developed from surface ectoderm.
  Two buds from proximal part of penile urethera
  will form bulbo-uretheral glands.

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Fate of primitive urogenital sinus A-
Vesicouretheral canal -Forms most of urinary
bladder in both sex. -Female urethera. -Upper ½
of prostatic urethera. N.B. Absorbed mesonephric
ducts forms -Trigone of the bladder. -Back of
femal urethera. -Back of upper ½ of prostatic
urethera.
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B- Pelvic part of defenitive urogenital
sinus Forms lower ½ of prostatic urethera and
membranous urethera. C- Phalic part of definitive
urogenital sinus - Forms uretheral plate which
is transformed into uretheral canal that form the
penile urethera except in glans penis which is
developed from cord of ectodermal cells which
becomes canalized and communicates with rest of
urethera.
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CONGENITAL ANOMALIES OF URETHERA

• Epispadius when urethera opens into the upper
  surface of penis.
• Hypospadius when urethera opens into lower
  surface of penis.