UG Development 1

Question 1

What are the primordia for the urogenital system?

Answer 1

• intermediate column mesoderm
• splanchnopleure of the hindgut

Question 2

What does the intermediate column of the UG system develop into during weeks 3-5?

Answer 2

• urogenital ridge along its length:
  
  • medial gonadal ridge
  • lateral nephrogenic cord

Question 3

What happens to the primary sex cords during early development (3-5 weeks)?

Answer 3

• grow into underlying mesenchyme
• forms the medulla of the primitive gonad

Question 4

What happens to the primary germ cells during early development (3-5 weeks)?

Answer 4

Migrate from the gut tube into the gonadal ridge

Question 5

Later development (5-8 weeks)**

Answer 5

• division of the cloaca
  
  • cloaca expands and becomes:
    • rectum
    • urogenital sinus
  • paramesonephric (mullerian) ducts invaginate on lateral surface of each UG ridge
    
    • fuse in the midline to form a uterovaginal primordium
    • conncets with the UG sinus
  • Genital tubercle develops cranial to the cloacal membrane - becomes UG and anal membranes
• ascent of the permanent kidney
  
  • migrates from pelvis to posterior abdominal wall
• formation of the sexually “indifferent” stage