ENLARGEMENT OF THE AMPULLARY GLAND AND SEMINAL-VESICLE, BUT NOT THE PROSTATE IN INT-2 FGF-3 TRANSGENIC MICE/

Expression of the int2/F gf-3 gene occurs during normal embryonic deve lopment and is associated with mammary cancer in mice. Overexpression of this gene under the control of the mouse mammary tumor virus long t erminal repeat (MMTV-LTR) in males was reported to result in prostatic enlargement. In this report male Fgf-3-overexpressing mice were shown to have enlarged ampullary glands, seminal vesicles, and ductus defer ens; there was extensive epithelial hyperplasia in the ampullary gland s and seminal vesicles. The prostates of these animals were of normal size and histology. The transgene was expressed in all of the enlarged organs, which are derived exclusively from the Wolffian duct. Male se condary sex organs derived from the urogenital sinus, e.g., the ventra l prostate, coagulating gland, and bulbourethral glands, were normal a nd did not express the MMTV-LTR-driven Fgf-3 transgene. A dorsolateral prostate was also morphologically normal but did express the transgen e. This study underscores the importance of careful organ identificati on in transgenic models in which gross organ enlargement or distortion occurs. It also highlights the heterogeneity of the response to Fgf-3 among the secondary sex organs and even within the prostate itself.