Spermatogonial stem cells (SSCs) are in the beginning of a complex process in which they transmit genetic information from generation to generation. Any failure in this process can result in infertility. It has been suggested that transplantation of spermatogonial stem cells, following their maintenance and culturing, may restore fertility in some infertile patients. Because fertility restoration through SSCs transplantation has been successfully achieved in animal experiments, we hope human studies can follow in the near future. The isolation and cultivation of SSCs help us study their biological characteristics and their application in therapeutic approaches. In this review, we studied spermatogenesis in rodents and humans. We also compared markers and different SSC culture systems in both.