Testicular Endothelial Cells (TEC), located in the mesonephros, migrate in the developing embryo from the mesonephros to form the testis vasculature during the process of testis cord formation. Migrating endothelial cells are also essential because they initiate cord formation by creating partitions for the Sertoli and Germ cells. Disrupting testis vascular development blocks testis cord formation and thereby prevents proper structural development of the testis. In addition, they have similar properties to brain endothelial cells and contribute to the establishment of the blood-testis barrier (BTB). Cultured Human TEC (HTEC) are a useful in vitro model to understand vascular defects in testis dysgenesis. They may also provide new insight for treatment of male reproductive disorders. Human Testicular Endothelial Cells are also useful tools to develop disease models for High Throughput and High Content Screening.