Editing Disorders of Sexual Differentiation (section)

==== Gonadal Stage of Differentiation ====
* '''During the first 6 weeks of embryonic development, the gonoads (gonadal ridge, germ cells, internal ducts, and external genitalia)''' '''are bipotential in both 46,XY and 46,XX embryos'''
** '''Posterior to the degenerating pronephros (primary kidney), the mesonephric/wolffian duct develops and extends in an anteroposterior direction.'''
*** '''The metanephros arises from inductive interactions between the ureteric bud that branches from the caudal wolffian duct and mesenchyme.'''
** '''Soon after formation of the wolffian duct, the paramesonephric/mullerian duct grows rostral to caudal, adjacent lateral the wolffian duct until the duct joins at the urogenital sinus.'''
* '''Under the genetic influences of SRY, the bipotential gonadal ridges differentiate into either ovaries or testes, and germ cells develop into either oocytes or spermatocytes.'''
** '''In the absence of SRY, ovarian organogenesis results.'''
*** '''Duplicate copies of at least one X-chromosomal locus are necessary (which presumably explains the dysgenetic ovaries in the 45,XO Turner syndrome patients)''' '''for development of the ovary.'''
** '''The precise moment at which this occurs remains unknown.'''
* '''In response to SRY, differentiation of Sertoli cells is noted at 6-7 weeks’ gestation.'''
* '''Germ cells reach a maximum endowment of 20 million cells by 20 weeks’ gestation'''