Development of biological tools to study claudins in the male reproductive tract.

It is estimated that between 12 and 15% of couples are infertile. More than half of these are related to problems associated with male reproductive dysfunction. Of those, 40% occur from idiopathic or unexplained causes. While spermatozoa are formed in the testis, testicular spermatozoa are immature and cannot swim or fertilize. These critical functions are acquired as spermatozoa transit through the epididymis in the specific luminal environment created in part by the tight junctions of the blood-epididymis barrier. To understand the normal and pathological conditions attributable to human and animal epididymal function, we have needed to develop biological tools to characterize the physiological, cellular, and molecular functions of tight junctions and claudins (Cldns) in the epididymis. We have shown that by developing epididymal cell lines we have gained valuable insight into the functions of epididymal Cldns, the regulation of the Cldn1 gene and how these can be mistargeted in infertile men. Here we describe some of the techniques that have been used to address these critical aspects of epididymal Cldns.