Virilization of the urogenital sinus of the tammar wallaby is not unique to 5α-androstane-3α,17β-diol

The androgen 5α-androstane-3α,17β-diol (5α-adiol) is synthesized in testes and secreted into plasma of male tammar wallaby pouch young and appears to virilize the urogenital sinus. To provide insight into its mechanism of action, a dose response study showed that administration of 1 μg 5α-adiol monoenanthate per g body wt. per week for 3 weeks to 24-day-old female pouch young induced prostate bud formation equivalent to that of males of the same age. Administration of this same dose of the enanthates of testosterone, dihydrotestosterone, and 5α-adiol to female pouch young caused equivalent virilization of the urogenital sinus. The fact that 5α-adiol does not exert a unique effect, together with our earlier findings in this species that 5α-adiol and testosterone are converted to dihydrotestosterone in the urogenital sinus and that virilization of the urogenital sinus is prevented by the androgen receptor antagonist flutamide, suggest that 5α-adiol is a circulating precursor for dihydrotestosterone formation in this tissue.