Cystic fibrosis (CF) is an inherited disease that affects multiple organs, including reproductive system. At least 97% of men with CF are infertile, in most cases due to congenital bilateral absence of the vas deferens (CBAVD). However, duct obstruction in CF is not the only reason for male infertility, suggesting that cystic fibrosis transmembrane conductance regulator (CFTR) plays an important role in production and maturation of sperm. My current study uses primary cultures of human epididymis epithelial cells and developed three-dimensional culture models to address how CFTR regulates normal tubule function in the epididymis. My goals are to understand the mechanisms of CFTR and other ion channels regulated epithelial function and tubulogenesis in the human epididymis.