Urogenital development

Question 1

Formation of bladder

Answer 1

-Bladder formed from allantois (endoderm of hind gut)

Question 2

Formation of the kidneys

Answer 2

• Mesodermal component of urogenital (UG) septum is derived from intermediate mesoderm
• Mesonephros (nesonephric ducts, tubules, and glomeruli) is derived from the mesoderm (not endoderm)
• Mesonephros regresses eventually, but before this there is budding of the metanephros which will be the mature kidneys

Question 3

Repositioning of the kidneys

Answer 3

• From their original sacral position they ascend to their final lumbar position to reside in their retroperitoneal position
• Adrenal glands do not ascend with kidneys but form once kidneys are ascended
• Fetal urine elimination: the UG membrane breaks down and allows continuity btwn the amniotic fluid and urinary system
• Waste is transported to the amniotic fluid and then taken up by placenta

Question 4

Development of genital system

Answer 4

• Paramesonephric ducts are parallel to mesonephric ducts
• In males: paramesonephric ducts regress entirely and the gonads are formed from the mesonephros (the rest of the mesonephros regresses)
• In females: the paramesonephric ducts are maintained and become the fallopian tubes
• The mesonephric ducts regress, but before this part of them become the ovaries

Question 5

External genital development

Answer 5

• Males: phallus extends to form pernis, UG folds fuse along the ventral midline to enclose the penile urethra
• Labiosacral swellings fuse to form scrotum
• Females: phallus becomes clitoris, UG folds remain unfused and become labia minora, labiosacral swelling remain unfused to be the labia majora