The role of androgens in the epithelio‐mesenchymal interactions involved in prostatic morphogenesis in embryonic mice

Standard tissue culture and epithelio‐mesenchymal separation and recombination techniques were applied to the question of sex determination of the male urogenital sinus of embryonic mice. Explants of urogenital sinuses from 12‐ to 17‐day old embryos were cultured in an androgen‐free environment to a gestational age equivalency of 18 to 20 days. The developmental response of these explants led to the following conclusions: (1) Androgens are necessary for initiation of prostatic bud outgrowth; (2) The effect of androgens can be demonstrated at the stage when the fetal testis begins to secrete androgens; and (3) Prior to the appearance of prostatic buds, the urogenital sinus has the capacity to pursue that developmental end‐point independently of further androgen stimulation. In addition, the developmental response of recombinants composed of androgen‐treated and untreated epithelium and mesenchyme from the urogenital sinus has shown that it is the epithelium which is primarily determined by androgens during prostatic morphogenesis.