author(s)
Rameez Ali, Shahzada Mudasir Rashid, Muneeb U Rehman, Masrat Rashid, Rayeesa Ali and Nowsheen Qadri

abstract
Differentiation of germ cells in the testes originates from a constantly renewed small pool of stem cells which give rise to the first differentiated spermatogonia. Spermatogonia are the only cells of the germ line, which proliferate in adulthood and offer interesting applications as they are potentially totipotent and immortal cells. They are committed for gene transfer to next generations via the process of fertilization of ovum by the spermatozoa, which is sequel of a sequence of events called spermatogenesis. DNA duplication and mitotic divisions always inherit risk for DNA damage, the pool of spermatogonial stem cells thus present an entry point for changes to the integrity of the genome and offer a pathway for genetic engineering of the male gem line. Spermatogonial stem cell transplantation from a fertile donor male into the somniferous tubules of infertile recipients can result in donor-derived sperm production. The application of this method in farm animals and humans has been the subject of increasing number of studies, mostly because of its potential as an alternative strategy in producing transgenic livestock with higher efficiency and less time; pertinently it will pave the way and ray of hope for individuals having infertility especially with cancer patients besides fertility preservation.