Spermatogonial stem cells （SSCs） are a type of adult stem cell found in male mammals.These cells have the capacity for self renewal and are capable of differentiating in the niche of testis.They are also the only adult stem cells in a normal postnatal body that undergo self-renewal throughout life,transferring genetic information to the offspring.Since a technique for transplanting SSCs was first described by Brinster and his colleagues in 1994,more and more researchers have become interested in exploring the possibility of utilizing adult SSCs to generate transgenic animals.In this mini-review,we attempt to summarize the current research progress in the area of spermatogonial stem cells including the source,types and differentiation of the SSCs,and the application on transgenic animals,with a particular focus on the strategy of SSCs delivery including seminiferous tubule injection and spermatogonial stem cell transplantation.
MicroRNAs （miRNAs）are small endogenous non-protein coding RNAs that range in size from 19-25 nucleotides. Thousands of miRNA genes have been identified in a variety of organisms, suggesting genetic exchange and distribution among species, miRNAs negatively regulate gene expression by binding to the 3＂-untranslated regions （3＂-UTRs） of their target genes and play an important role in growth, development and the occurrence of diseases. In this review, we summarize the recent advances in the understanding of the role of miRNAs in exosomes and their therapeutic potential, as well as provide an overview of the basic characteristics of miRNAs.
