1. Department of Urology; Faculty of Medicine; University of Tsukuba; Tsukuba Ibaraki Japan
2. Department of Urology; Tsukuba Medical Center Hospital; Tsukuba Ibaraki Japan
3. Division of Male Infertility Center for Human Reproduction; Sanno Hospital; Tokyo Japan
4. Department of Urology; School of Medicine; International University of Health and Welfare; Narita Chiba Japan