Spermatogenesis is a complex, well-organized process including proliferation, differentiation, apoptosis, and morphogenesis through which differentiating daughter cells of spermatogonial stem cells develop into mature sperm (1 ,2 ). In men, this process requires approx 64 d, 52 d in the rat, and 35 d in the mouse. This process in mammals occurs in a highly coordinated fashion within the seminiferous epithelium inside the seminiferous tubule. Spermatogenesis can be divided into three phases.
