Practice question

Wnt4 is secreted glycoprotein of Wnt family functioning as pivotal ovary-determining signal. Expressed in bipotential gonad and upregulated specifically in XX somatic cells, Wnt4 activates canonical β-catenin cascade via Frizzled receptors, leading to stabilization of β-catenin and transcription of Dax1, Fst and Foxl2. This promotes granulosa fate, survival of germ cells entering meiosis, vascular patterning typical of ovary and maintenance of Müllerian ducts. Wnt4 knockout XX mice exhibit partial female-to-male reversal with Wolffian duct persistence, androgen synthesis, oocyte loss and ectopic testis cords, revealing requirement.