Fig. 4.

Models of prostate bud induction. (A) In the andromedin model, androgen signaling through androgen receptor (AR) expressed in the urogenital mesenchyme (UGM) results in the production of one or more signaling factors (andromedins) that directly induce prostate budding in the adjacent urogenital epithelium (UGE). (B) In the smooth muscle model, signals that promote epithelial budding occur constitutively, and androgen signaling within the mesenchyme indirectly controls this process. In this model, androgen signaling is proposed to regulate the differentiation of smooth muscle around the emerging prostate ducts, thereby inhibiting further epithelial budding in regions where smooth muscle has already formed. DHT, dihydrotestosterone.