Background The piwi family genes are highly conserved during evolution and play a crucial role in stem cell self-renewal, gametogenesis, and RNA interference in diverse organisms ranging from Arabidopsis to humans. Piwil2, also known as Hili, is one of the four human homologues of piwi. Piwil2 was found in germ cells of adult testis, suggesting that this gene functions in spermatogonial stem ce...

Spermatogonial stem cells represent a self-renewing population of spermatogonia, and continuous division of these cells supports spermatogenesis throughout the life of adult male animals. Previous attempts to introduce adenovirus vectors into spermatogenic cells, including spermatogonial stem cells, have failed to yield evidence of infection, suggesting that male germ cells may be resistant to ...

Potential therapeutic use of stem cells in the treatment of human diseases depends on our ability to control the balance of their differentiation and self-renewal in vitro and in vivo. The stem cell "niche," or specialized microenvironment, is now recognized as one of the major contributors to this regulation in many species. Our recent study, which was reported in Nature, was the first to demo...

BACKGROUND Spermatogonial stem cells (SSCs), a subset of undifferentiated type A spermatogonia, are the foundation of complex process of spermatogenesis and could be propagated in vitro culture conditions for long time for germ cell transplantation and fertility preservation. OBJECTIVE The aim of this study was in vitro propagation of human spermatogonial stem cells (SSCs) and improvement of ...

The origin and development of the spermatogenic cell lineage is reviewed, as well as spermatogonial kinetics in adult nonprimate mammals in relation to the cycle of the seminiferous epithelium, the emphasis being on spermatogonial stem cells. A hypothesis is presented for the transition from foetal germ cells, gonocytes, to adult type spermatogonia at the start of spermatogenesis. An overview i...

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 restorati...

OBJECTIVE The properties of self-renewal and division in spermatogonial stem cells (SSCs) support spermatogenesis. There is a number of reported methods for in vitro SSC culture systems. The development of a culture system that effectively supports isolation and selfrenewal of germline stem cells (GSCs) is of tremendous benefit for clinical trials, experimental research, and as potential treatm...

OBJECTIVE(S) Transplantation quality improvement and reduction of cellular damage are important goals that are now considered by researchers. Melatonin is secreted from the pineal gland and some organs such as testes. According to beneficial effects of melatonin (such as its antioxidant and antiapoptotic properties), researchers have proposed that the use of melatonin may improve transplantatio...

INTRODUCTION Patients faced with infertility due to spermatogonial stem cell loss have currently semen cryobanking as only option for fertility preservation. A growing group of patients cannot benefit from this strategy as they are devoid of spermatozoa or even of any spermatogenic cell at the time of diagnosis. We therefore aimed at investigating alternative strategies to preserve or restore f...