I n males, sperm production begins at puberty and lasts throughout reproductive life. This implies that a population of germ stem cells/progenitors must be maintained, amplified and differentiate throughout life to enable the continuous supply of sperm. Spermatogenesis is indeed divided into three phases: a proliferative phase, a meiotic phase and a postmeiotic spermiogenic phase. In the prolif...

BACKGROUND: Spermatogonial stem cells (SSCs) are infrequentself-renewing cells among the type A spermatogoniawithin the seminiferous tubules and are the basis of spermatogenesisin mammalian testis. An adequate number of SSCs is aprimary requirement for the study of their behavior, regulation, andfurther biomanipulation. OBJECTIVES: In this paper, we studiedthe development of the primary co-cult...

BACKGROUND Spermatogonia are highly tolerant to reactive oxygen species (ROS) attack while advanced-stage germ cells such as spermatozoa are much more susceptible, but the precise reason for this variation in ROS tolerance remains unknown. METHODOLOGY/PRINCIPAL FINDINGS Using the Japanese eel testicular culture system that enables a complete spermatogenesis in vitro, we report that advanced-s...

BACKGROUND A key step in studying the biology of spermatogonia is to determine their global gene expression profile. However, disassociation of these cells from the testis may alter their profile to a considerable degree. To characterize the molecular phenotype of human spermatogonia, including spermatogonial stem cells (SSCs), within their cognate microenvironment, a rare subtype of human defe...

H-Y antigen negative XOSxrb mice, like their H-Y positive XOSxra counterparts, have testes; but, in contrast to XOSxra males, XOSxrb testes almost totally lack meiotic and postmeiotic stages of spermatogenesis. The quantitative analysis of the testes of XOSxrb males and their XY +/- Sxrb sibs, described in the present study, identified two distinct steps in this spermatogenic failure. First, th...

Previous work in dogfish, Scyliorhinus canicula, has identified the testicular germinative area as the spermatogonial stem cell niche. In the present study, an in vitro co-culture system of spermatogonia and somatic cells from the germinative area was developed. Long-term maintenance of spermatogonia has been successful, and addition of GDNF has promoted the development of clones of spermatogon...

H-Y antigen negative XOSxr mice, like their H-Y positive XOSxr" counterparts, have testes; but, in contrast to XOSxr" males, XOSxr" testes almost totally lack meiotic and postmeiotic stages of spermatogenesis. The quantitative analysis of the testes of XOSxr males and their XY±Sxr sibs, described in. the present study, identified two distinct steps in this spermatogenic failure. First, there wa...

Spermatogonia- stem cells and progenitors of adult spermatogenesis- are killed through a p53-regulated apoptotic process after gamma-irradiation but the death effectors are still poorly characterized. Our data demonstrate that both intrinsic and extrinsic apoptotic pathways are involved, and especially that spermatogonia can be split into two main populations, according to apoptotic effectors. ...

The retinoblastoma tumor suppressor gene Rb is essential for maintaining the quiescence and for regulating the differentiation of somatic stem cells. Inactivation of Rb in somatic stem cells typically leads to their overexpansion, often followed by increased apoptosis, defective terminal differentiation, and tumor formation. However, Rb's roles in germ-line stem cells have not been explored. We...

All-trans retinoic acid (ATRA) is instrumental to male germ cell differentiation, but its mechanism of action remains elusive. To address this question, we have analyzed the phenotypes of mice lacking, in spermatogonia, all rexinoid receptors (RXRA, RXRB and RXRG) or all ATRA receptors (RARA, RARB and RARG). We demonstrate that the combined ablation of RXRA and RXRB in spermatogonia recapitulat...