Swyer Syndrome (46,XY Complete Gonadal Dysgenesis)

A 16-year-old phenotypically female adolescent presents with primary amenorrhea, tall stature (178 cm, 97th percentile), sparse pubic and axillary hair, and hypoplastic uterus with bilateral streak gonads on imaging. Laboratory studies reveal elevated FSH (68 mIU/mL) and LH (42 mIU/mL), undetectable estradiol, and undetectable AMH. Karyotype analysis shows 46,XY. The structure marked **B** in the diagram carries a loss-of-function mutation at Yp11.3. Which of the following best explains the pathophysiology of this patient's condition?