1. Division of the Urogenital System
• Urinary System
• Genital System
2. Embryological Development of the Urogenital System
• Intermediate Mesoderm Origin
• Both the urinary and genital systems develop from the intermediate
mesoderm.
• Occurs along the posterior abdominal wall.
3. Formation of the Urogenital Ridge
• Urogenital Ridge Formation
• Forms on each side of the dorsal aorta during the 5th week.
• Nephrogenic Cord (Lateral Part)
• Gives rise to the urinary system.
• Gonadal Ridge (Medial Part)
• Gives rise to the genital system.
4. Development of Ducts
• Mesonephric Duct
• Functions in the male genital system.
• Remnant exists in the female genital system.
• Paramesonephric Duct
• Functions in the female genital system.
• Remnant exists in the male genital system.
5. Origin of Germ Cells
from the epiblast to dorsal mesenter
• Derived from the Posterior Wall of the Yolk Sac of hindgut
• Some endodermal cells migrate from the posterior wall of the yolk sac.
• Migration to Gonadal Elevations
• These cells move towards the gonadal elevations during development.
,1. Gonadal Development 3 things: mesothelium linning
the posterior abdominal wall
underline mesnchyme
• Origin of Gonads primordial germ cells
• Derived from the gonadal ridges, which are located lateral to the aorta and
medial to the nephrogenic cord.
• Formation of Gonadal Ridge
• The gonadal ridge produces a bulge on the medial side of the nephrogenic
cord bilaterally.
• This bulge results from the proliferation of epithelium and underlying
mesenchyme.
2. Germ Cell Migration
• Appearance in Genital Ridges
• Germ cells appear in the genital ridges during the sixth week of development.
• Migration Path
• During the 4th week, germ cells begin their migration along the hindgut.
• They arrive at the primitive gonads during the fifth week.
• Germ cells invade the genital ridges in the sixth week.
, 1. Formation of Primitive Sex Cords
medullary cord in male
seminferous tubule
• Development During the 7th Week
• Fingerlike epithelial cords, known as the primitive sex cords, grow into the
underlying mesenchyme during the 7th week.
• Indifferent Gonad Structure Thickening of celomic epithelium along the medial aspect of
mesonephron
• At this stage, the indifferent gonad consists of an outer cortex and an internal
Development of Sertoli Cells:
medulla in both males and females. • The epithelial cells of the primary sex cords
differentiate into Sertoli cells.
• Sertoli cells play a critical role in supporting
germ cell development and forming the blood-testis
2. Origin of Primitive Sex Cords barrier.
• They also produce Anti-Müllerian Hormone
(AMH), which leads to the regression of the Müllerian
ducts (which would otherwise develop into female
• Proliferation of Mesodermal Epithelium reproductive structures)
• The primitive sex cords originate from the proliferation of the mesodermal
epithelium of the two gonadal ridges.
• Development of Leydig
At 7th either develop into male or female genitalia
Cells (8th Week):
• The mesenchymal
cells in the gonadal ridge
differentiate into Leydig cells,
which are found in the
interstitial tissue between the
seminiferous tubules.
• Leydig cells begin
producing testosterone around
1. Development of Testis in Male Embryo (XY) the 8th week
• Continued Proliferation of Primitive Sex Cords
• If the embryo is genetically male (XY), the primitive sex cords continue to
proliferate.
• Formation of Testis (Medullary Cords)
• These cords penetrate deep into the medulla to form the testis, also known as
the medullary cords.
• Degeneration of the Cortex
• In male embryos, the cortex degenerates as the medullary cords develop.
• Urinary System
• Genital System
2. Embryological Development of the Urogenital System
• Intermediate Mesoderm Origin
• Both the urinary and genital systems develop from the intermediate
mesoderm.
• Occurs along the posterior abdominal wall.
3. Formation of the Urogenital Ridge
• Urogenital Ridge Formation
• Forms on each side of the dorsal aorta during the 5th week.
• Nephrogenic Cord (Lateral Part)
• Gives rise to the urinary system.
• Gonadal Ridge (Medial Part)
• Gives rise to the genital system.
4. Development of Ducts
• Mesonephric Duct
• Functions in the male genital system.
• Remnant exists in the female genital system.
• Paramesonephric Duct
• Functions in the female genital system.
• Remnant exists in the male genital system.
5. Origin of Germ Cells
from the epiblast to dorsal mesenter
• Derived from the Posterior Wall of the Yolk Sac of hindgut
• Some endodermal cells migrate from the posterior wall of the yolk sac.
• Migration to Gonadal Elevations
• These cells move towards the gonadal elevations during development.
,1. Gonadal Development 3 things: mesothelium linning
the posterior abdominal wall
underline mesnchyme
• Origin of Gonads primordial germ cells
• Derived from the gonadal ridges, which are located lateral to the aorta and
medial to the nephrogenic cord.
• Formation of Gonadal Ridge
• The gonadal ridge produces a bulge on the medial side of the nephrogenic
cord bilaterally.
• This bulge results from the proliferation of epithelium and underlying
mesenchyme.
2. Germ Cell Migration
• Appearance in Genital Ridges
• Germ cells appear in the genital ridges during the sixth week of development.
• Migration Path
• During the 4th week, germ cells begin their migration along the hindgut.
• They arrive at the primitive gonads during the fifth week.
• Germ cells invade the genital ridges in the sixth week.
, 1. Formation of Primitive Sex Cords
medullary cord in male
seminferous tubule
• Development During the 7th Week
• Fingerlike epithelial cords, known as the primitive sex cords, grow into the
underlying mesenchyme during the 7th week.
• Indifferent Gonad Structure Thickening of celomic epithelium along the medial aspect of
mesonephron
• At this stage, the indifferent gonad consists of an outer cortex and an internal
Development of Sertoli Cells:
medulla in both males and females. • The epithelial cells of the primary sex cords
differentiate into Sertoli cells.
• Sertoli cells play a critical role in supporting
germ cell development and forming the blood-testis
2. Origin of Primitive Sex Cords barrier.
• They also produce Anti-Müllerian Hormone
(AMH), which leads to the regression of the Müllerian
ducts (which would otherwise develop into female
• Proliferation of Mesodermal Epithelium reproductive structures)
• The primitive sex cords originate from the proliferation of the mesodermal
epithelium of the two gonadal ridges.
• Development of Leydig
At 7th either develop into male or female genitalia
Cells (8th Week):
• The mesenchymal
cells in the gonadal ridge
differentiate into Leydig cells,
which are found in the
interstitial tissue between the
seminiferous tubules.
• Leydig cells begin
producing testosterone around
1. Development of Testis in Male Embryo (XY) the 8th week
• Continued Proliferation of Primitive Sex Cords
• If the embryo is genetically male (XY), the primitive sex cords continue to
proliferate.
• Formation of Testis (Medullary Cords)
• These cords penetrate deep into the medulla to form the testis, also known as
the medullary cords.
• Degeneration of the Cortex
• In male embryos, the cortex degenerates as the medullary cords develop.
