Practice question

Primary sex determination describes initial decision within bipotential gonad whether to become testis or ovary, distinct from secondary sexual characteristics. Process occurs around seventh week in humans when Sry in XY gonads commits supporting lineage to Sertoli fate through Sox9 upregulation and ovary pathway via Wnt4/β-catenin in XX, shaping gonadal architecture. Gonad then secretes hormones Anti-Müllerian hormone and testosterone or estrogen orchestrating secondary determination of internal ducts, external genitalia, brain and general habitus. Primary event therefore corresponds to gonads differentiating into testes or ovaries.