- An epididymis-specific beta-defensin is important for the initiation of sperm maturation. Zhou, C.X., Zhang, Y.L., Xiao, L., Zheng, M., Leung, K.M., Chan, M.Y., Lo, P.S., Tsang, L.L., Wong, H.Y., Ho, L.S., Chung, Y.W., Chan, H.C. Nat. Cell Biol. (2004)