Porcine Sertoli Cell Proliferation after Androgen Receptor Inactivation1 Running Title: Androgens and Sertoli Cell Proliferation in Pigs

Sertoli cell proliferation in neonatal boars is potentially androgen-dependent. Hence, the immediate objective was to evaluate effects of androgen receptor-mediated signaling on the first wave of Sertoli cell proliferation. The experimental design employed littermate pairs of boars with one member assigned to receive a daily oral dose of flutamide, an androgen receptor antagonist, beginning at one week of age and the littermate the canola oil vehicle. Experiment one examined the response at 6.5 weeks of age, after completion of the first wave of Sertoli cell proliferation and experiment two examined the response at 11 weeks of age after initiation of the second wave of Sertoli cell proliferation. Experiment three was designed to evaluate initial responses at 2, 3, or 4 wk of age. Additional littermates from four of the litters evaluated at 2 wk of age were hemicastrated at 8 days of age. Testis weight increased approximately 50 % in the flutamide-treated boars compared with vehicle-treated littermates (P = 0.01) by 6.5 wk of age. Approximately 80 % more Sertoli cells/testis were present in flutamide-treated boars at 6.5 wk o