Practice question

Wnt4 signaling through Frizzled receptors and Lrp5/6 co-receptors stabilizes β-catenin in XX somatic precursors. Canonical pathway directly upregulates genes required for ovarian morphogenesis including Bmp2, Follistatin that blocks testis coelomic vessel formation, and Dax1 that antagonizes Sox9. Simultaneously it suppresses male steroidogenic program preventing ectopic testosterone production and maintains Müllerian duct integrity. Continued Wnt4 supports granulosa differentiation, oocyte survival in meiotic arrest and follicle formation. Loss produces partial masculinization revealing indispensability. Thus Wnt4 promotes ovary development as central female determinant opposing testis.