Polycystic Ovarian Morphology (PCOS — Rotterdam)

A 24-year-old nulliparous woman with irregular menstrual cycles (45–90 days), hirsutism, acne, and infertility for 14 months presents for evaluation. Transvaginal ultrasound shows bilaterally enlarged ovaries with the characteristic finding marked **A** in the diagram — more than 20 small antral follicles (2–9 mm) arranged peripherally around increased central stromal echogenicity. She also has elevated LH:FSH ratio (2.5:1), elevated fasting insulin, and normal TSH and 17-OH-progesterone. Which of the following best explains the pathophysiological basis for the peripheral follicular arrangement marked **A** in PCOS?