A new model system for studying androgen-induced growth and morphogenesis in vitro: the bulbourethral gland

An organ culture system was devised for neonatal mouse bulbourethral glands (BUGs) in which androgen-dependent development parallels that in vivo. BUGs from 0-day-old (day of birth) mice were grown on Millipore filters placed on metal grids in petri dishes for 3 or 6 days in Dulbecco's Modified Eagle's Medium-Ham's F-12 medium (1:1) containing 10% fetal bovine serum. In medium supplemented with testosterone (T; 10(-7) or 10(-8) M), growth and epithelial morphogenesis of the cultured BUGs were comparable to those of the gland in situ. At lower doses of T (10(-9) -10(-12) M), BUGs showed dose-dependent decreases in the rate of growth and degree of epithelial morphogenesis. BUGs cultured without T contained only 38% as much DNA as those in T-supplemented medium, and epithelial morphogenesis did not occur. Thus, BUG development in vitro was dependent on androgens. The continued, albeit reduced, growth in cultures without T indicates that growth is also partially independent of androgens, but epithelial branching morphogenesis is totally dependent on this hormone. Growth and epithelial morphogenesis were reinitiated in glands that had developed in the absence of T, either in vivo or in vitro, by culturing the BUGs for 3 days in T-containing medium. The growth of BUGs in a serum-free medium with or without T paralleled that in comparable serum-containing cultures in vitro and in normal and castrated animals in situ. Coincubation of BUGs with T and 390 MSD (17 beta-N,N-diisopropylcarbamoyl-4-aza-5 alpha-androstan-3-one), an inhibitor of the enzyme 5 alpha-reductase, resulted in retarded development, indicating that T must be converted to 5 alpha-dihydrotestosterone (DHT) to promote normal BUG growth. Additionally, DHT (10(-8) M) alone could substitute for T in promoting BUG development. Thus, DHT must be the proximal androgen for BUG growth. The BUG is an excellent model system for examining androgen-dependent development and should be useful for studying epithelial morphogenesis, growth, and hormonal effects in vitro.