Induction of functional cytodifferentiation in the epithelium of tissue recombinants : II. Instructive induction of Wolffian duct epithelia by neonatal seminal vesicle mesenchyme*

When grown as renal grafts in adult male hosts, the upper (cranial), middle and lower (caudal) portions of fetal mouse and rat Wolffian ducts developed into epididymis, epididymis plus ductus deferens, and seminal vesicle, respectively. In heterotypic tissue recombinants, the epithelia from upper and middle Wolffian ducts were instructively induced to undergo seminal vesicle morphogenesis by neonatal seminal vesicle mesenchyme. Functional cytodifferentiation was examined in these recombinants using antibodies against major androgen-dependent, seminal vesicle-specific secretory proteins. The instructively induced Wolffian duct epithelia synthesized normal amounts of all of the secretory proteins characteristic of mature seminal vesicles, as judged by immunocytochemistry on tissue sections and gel electrophoresis plus immunoblotting of secretions extracted from the recombinants. In heterospecific recombinants composed of rat and mouse tissues, the seminal vesicle proteins induced were specific for the species that had provided the epithelium. This showed that the seminal vesicle epithelium in the recombinants was derived from instructively induced Wolffian duct epithelium and not from epithelial contamination of the mesenchymal inductor. Upper Wolffian duct epithelium, instructively induced to undergo seminal vesicle morphogenesis, did not express epididymis-specific secretory proteins, showing that its normal development had been simultaneously repressed.