Development of GENITAL DUCTS
Indifferent stage:
Initially both male & female embryos have 2 pairs of genital ducts:
• mesonephric (Wolffian) ducts.
• paramesonephric (Mullerian) ducts.
• These ducts develop from intermediate mesoderm on each side, & extend
longitudinally from gonad to urogenital sinus of cloaca
Different stage:
• SRY induces differentiation of Sertoli & Leydig cells.
***Sertoli cells secrete Mullerian inhibiting substance (MIS) which causes
regression of paramesonephric (Mullerian) ducts.
***Leydig cells secrete Testosterone which causes differentiation of mesonephric
ducts & male external genitalia.
– As sex of embryo becomes differentiated, only one duct continues development
to form genital ducts while other degenerates:
– In males: mesonephric (Wolffian) duct persists, & other degenerates.
– In females: paramesonephric (Mullerian) duct persists, & other degenerates.
Indifferent stage:
Initially both male & female embryos have 2 pairs of genital ducts:
• mesonephric (Wolffian) ducts.
• paramesonephric (Mullerian) ducts.
• These ducts develop from intermediate mesoderm on each side, & extend
longitudinally from gonad to urogenital sinus of cloaca
Different stage:
• SRY induces differentiation of Sertoli & Leydig cells.
***Sertoli cells secrete Mullerian inhibiting substance (MIS) which causes
regression of paramesonephric (Mullerian) ducts.
***Leydig cells secrete Testosterone which causes differentiation of mesonephric
ducts & male external genitalia.
– As sex of embryo becomes differentiated, only one duct continues development
to form genital ducts while other degenerates:
– In males: mesonephric (Wolffian) duct persists, & other degenerates.
– In females: paramesonephric (Mullerian) duct persists, & other degenerates.
