Administration of 5α-Androstane-3α,17β-Diol to Female Tammar Wallaby Pouch Young Causes Development of a Mature Prostate and Male Urethra

Secretion of 5alpha-androstane-3alpha,17beta-diol (5alpha-adiol) by the testes of the tammar wallaby is responsible for initiation of prostatic development after d 20 in male pouch young. To ascertain the role of this hormone in the subsequent growth and differentiation of the prostate and in the development of the male phallus, 5alpha-adiol was administered to tammar female pouch young in two regimens. Administration of the hormone by mouth (8 microg/g body weight.wk) between d 70 and 150 of pouch life caused prostate development equivalent to that in d 150 males and promoted growth and differentiation of the penis, but not masculinization of the urethra. Treatment with a small dose of 5alpha-adiol enanthate (1 microg/g body weight.wk) from d 20-150 produced similar results. However, administration of larger doses of 5alpha-adiol enanthate (10 or 100 microg/g body weight.wk) from d 20-150 caused supraphysiological growth of the prostate, development of a male-type urethra, and penile growth. These results indicate that prostatic development and penile growth can be initiated over a wide time period, but that formation of a male urethra requires androgen action before d 70, when male penile differentiation begins. This further strengthens the hypothesis that 5alpha-adiol is the circulating androgen responsible in this species for virilization during development.