Transforming growth factor‐beta 2 heterozygous mutant mice exhibit Cowper's gland hyperplasia and cystic dilations of the gland ducts (Cowper's syringoceles)

Analyses of mutant mice with a deletion for the transforming growth factor beta 2 (Tgfβ2) gene revealed cysts in the perineal/scrotal region of male mice. We present evidence from in situ, light and electron microscopy that the cysts observed in Tgfβ2+/– heterozygous mice males derive from Cowper's gland tissue. The Cowper's glands of Tgfβ2+/– heterozygous mutant mice display all steps of glandular hyperplasia and cystic dilation. TGF‐β isoforms and TGF‐β receptor (TβR‐II) were localized immunocytochemically in sections of Cowper's glands. TGF‐β2 and TGF‐β3 were located predominantly in myoepithelial cells of the Cowper's gland whereas the TβRII was found in the plasma membrane of the acinar cells. TUNEL‐assays revealed that apoptotic cell death is significantly reduced in Cowper's glands of Tgfβ2+/– heterozygous mutant mice. The fact that Tgfβ2+/– heterozygous mutant mice exhibit hyperplasia of Cowper's gland epithelium and Cowper's gland cysts suggests a disturbance of epithelial–stromal interaction most likely due to reduced TGF‐β2 level, accompanied by a significant decrease in apoptosis.