Spermatogonial stem cells are the only stem cells in the body that transmit genetic information to offspring. Although growth factors responsible for self-renewal of these cells are known, the factors and mechanisms that attract and physically maintain these cells within their microenvironment are poorly understood. Mice with targeted disruption of Ets variant gene 5 (Etv5) show total loss of s...

We previously cultured fragments of newt testes in chemically defined media and showed that mammalian follicle-stimulating hormone (FSH) stimulates proliferation of spermatogonia as well as their differentiation into primary spermatocytes (Ji et al., 1992; Abe and Ji, 1994). Next, we indicated in cultures composed of spermatogonia and somatic cells (mainly Sertoli cells) that FSH stimulates ger...

background: niche cells, regulating spermatogonial stem cells (sscs) fate are believed to have a reciprocal communication with sscs. the present study was conducted to evaluate the effect of ssc elimination on the gene expression of glial cell line-derived neurotrophic factor (gdnf), fibroblast growth factor 2 (fgf2) and kit ligand (kitlg), which are the main growth factors regulating sscs deve...

BACKGROUND Spermatogonial expansion in man and non-human primates has been studied for decades. Controversy persists about the cell type representing the testicular stem cell and the exact kinetics of spermatogonial proliferation. We recently determined the starting point of spermatogenesis and proposed a model for clonal expansion of spermatogonia in adult macaques. Here we want to confirm the...

Mammalian spermatogenesis is maintained by a continuous supply of differentiating cells from self-renewing stem cells. The stem cell activity resides in a small subset of primitive germ cells, the undifferentiated spermatogonia. However, the relationship between the establishment of this population and the initiation of differentiation in the developing testes remains unclear. In this study, we...

A critical step of spermatogenesis is the entry of mitotic spermatogonia into meiosis. Progresses on these topics are hampered by the lack of an in vitro culture system allowing mouse spermatogonia differentiation and entry into meiosis. Previous studies have shown that mouse pachytene spermatocytes cultured in simulated microgravity (SM) undergo a spontaneous meiotic progression. Here we repor...

Continuity of cycling cell lineages relies on the activities of undifferentiated stem cell-containing subpopulations. Transition to a differentiating state must occur periodically in a fraction of the population to supply mature cells, coincident with maintenance of the undifferentiated state in others to sustain a foundational stem cell pool. At present, molecular mechanisms regulating these a...

Background: This study was conducted to identify and characterize repopulating spermatogonial stem cells (SSCs) in the adult human testes. Materials and Methods: Testes biopsies from obstructive azoospermic patients and normal segments of human testicular tissue were used. Flow cytometry, real time PCR and immunohistochemical analysis were performed. Purified human spermatogonia were transplant...

Background: Proliferation of spermatogonial stem cells (SSCs) can be a treatment for infertile men. Here, we design an efficient method based on culturing in the presence of Sertoli cells to improve the expression level of some specific spermatogonia stem cell genes during two weeks post culture. Materials and Methods: Cells were derived from neonatal (2-6 days old) mice testes and were cultur...

BACKGROUND Several studies have reported the generation of spermatogonia-derived pluripotent stem cells from human testes. The initial aim of the present study was the derivation of equivalent stem cells from an established and experimentally accessible non-human primate model, the common marmoset monkey (Callithrix jacchus). However, an essential prerequisite in the absence of transgenic repor...