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...

Telomerase inactivation causes loss of the male germline in worms, fish, and mice, indicating a conserved dependence on telomere maintenance in this cell lineage. Here, using telomerase reverse transcriptase (Tert) reporter mice, we found that very high telomerase expression is a hallmark of undifferentiated spermatogonia, the mitotic population where germline stem cells reside. We exploited th...

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...

Many salmonid species have recently become at risk of extinction. For fish species where eggs cannot be cryopreserved, establishment of techniques to preserve genetic resources other than egg and embryo cryopreservation is imperative. In the present study, spermatogonia from male trout were transplanted into the peritoneal cavity of newly hatched sterile triploid salmon. Transplanted trout sper...

The qualitative behaviour of spermatogenetic cells and Sertoli cells in the buffalo (Bubalus bubalis) was studied by identifying 8 stages of the seminiferous epithelium cycle based on meiotic division and morphology as well as the position of more mature spermatids. To achieve better results, stages 1, 2, 3, 4 and 8 were sub-divided. Six peaks of spermatogonial mitosis suggested six generations...

Background:Spermatogenesis is maintained by a pool of the spermatogonia. The group formed by As, Apr and Aal is known as undifferentiated type a spermatogonia (Aund). The Aal spermatogonia will differentiate, with no mitotic division, to the differentiating type A1 spermatogonia. The type A1 spermatogonia undergo 6 successive mitotic divisions to yield A2, A3, A4, intermediate-type (In), and ty...

The spermatogenic lineage is established after birth when gonocytes migrate to the basement membrane of seminiferous tubules and give rise to spermatogonial stem cells (SSC). In adults, SSCs reside within the population of undifferentiated spermatogonia (A(undiff)) that expands clonally from single cells (A(single)) to form pairs (A(paired)) and chains of 4, 8 and 16 A(aligned) spermatogonia. A...

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 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...