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.

Spermatogonial Stem Cell (SSC) technologies provide multiple opportunities for research in the field of biotechnology and regenerative medicine. The therapeutic use of Embryonic Stem Cells (ESCs) is restricted due to severe ethical and immunological concerns. Therefore, we need a new pluripotent cell type. Despite well-known role of germ cells in the gametogenesis, some facts apparently show their multipotentiality. In the present study, bovine SSCs were co-cultured with Sertoli cell for 7 days. Sertoli cells and SSCs were iden-tified by Vimentin and Oct-4 immunocytochemical staining method, respect-ively. In order to differentiate SSCs into osteoblasts, we used consecutive in-ducer media without separation of the colonies. We characterized osteoblasts using Alizarin red staining.

Spermatogonial stem cells (SSCs) form the basis of spermatogenesis resulting in the production of countless numbers of sperm throughout adulthood in a male. In addition to being extremely efficient, SSCs are unique in that they are the only stem cells in an adult body that can contribute genes to the next generation. These attributes point to the tremendous potential of SSCs as a source of genetic change in the progeny. Our knowledge of SSCs, however, began to dramatically increase only after a system for transplantation of these cells was developed by Ralph Brinster from the University of Pennsylvania in 1994. In this transplantation system, dissociated testis cells from a donor male are microinjected into the seminiferous tubules of the recipient testis. While the population of testicular donor cells may contain a heterogeneous mixture of different types of germ cells and somatic cells, only true spermatogonial stem cells can colonize and initiate new spermatogenesis in the recipient testis, making this transplantation system a functional assay for unequivocal detection of SSCs in a given population of testis cells. The process involves a selection step in which Sertoli cells recognize and allow SSCs to migrate from the lumen of the seminiferous tubule, where they are deposited, to the basal membrane which contains the stem cell niche. Ever since its advent, this transplantation system has played an instrumental role in hundreds of studies, greatly expanding the field of male reproductive biology and shaping up our current understanding of SSCs. This includes learning some crucial facts about SSCs, such as their ability to maintain developmental potential after long-term culture, cryopreservation, and genetic modification. This system not only has made it possible to study markers for SSCs but also for their continued self-renewal. We have also learned that: SSCs’ characteristics are conserved among closely-related species; SSCs have the ability resist a number of cytotoxic insults; can also be genetically modified; forced into proliferation in vitro; and made to differentiate into a number of cell lineages. These lessons have broaden our general knowledge of adult stem cells and provided potential alternatives to overcome some forms of male infertility.