Tissue recombinants of epithelium and stroma from embryonic and neonatal urogenital rudiments derived from wild‐type and femininized (Tfm/Y) mice were grown as grafts in intact male hosts and analyzed morphologically for androgenic response. When mesenchyme of embryonic wild‐type urogenital sinus (UGS) was associated with epithelium from embryonic wild‐type bladder (B), the epithelium developed into glandular structures resembling prostate. In the reciprocal recombinant (B mesenchyme + UGS epithelium) the response was mixed, half of the recombinants exhibited bladder morphology and half exhibited prostatic‐like morphology.

Vaginal‐like histogenesis occurred in UGS recombinants of androgen‐insensitive Tfm/Y mesenchyme and wild‐type epithelium, while prostatic morphology developed in reciprocal recombinants of wild‐type mesenchyme and Tfm/Y epithelium. These observations demonstrate (1) that the presence of wild‐type mesenchyme appears essential for expression of androgen‐dependent morphogenesis during embryonic periods; and (2) that Tfm/Y epithelium is capable of participating in an androgenic response. Conversely, in similar recombinants prepared with neonatal tissues, the presence of wild‐type urogenital stroma may not be required for expression of certain androgen‐dependent phenomena since maintenance of the height and cytodifferentiation of ductus deferens epithelium occurs even when this epithelium is associated with Tfm/Y urogenital stroma. It appears, therefore, that the requirement of urogenital epithelium for wild‐type (androgen sensitive) stroma may vary temporally.