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...

Undifferentiated spermatogonia comprise a pool of stem cells and progenitor cells that show heterogeneous expression of markers, including the cell surface receptor GFRα1. Technical challenges in isolation of GFRα1+ versus GFRα1- undifferentiated spermatogonia have precluded the comparative molecular characterization of these subpopulations and their functional evaluation as stem cells. Here, w...

Spermatogenesis in testes requires precise spermatogonia differentiation. Spermatocytes lacking the Rad9a gene are arrested in pachytene prophase, implying a possible role for RAD9A in spermatogonia differentiation. However, numerous RAD9A-positive pachytene spermatocytes are still observed in mouse testes following Rad9a excision using the Stra8-Cre system, and it is unclear whether Rad9a dele...

Adult male medaka (Oryzias latipes) were exposed to 10 ppm of cadmium for 96 h, and the testes were examined histopathologically. Numerous apoptotic cells were found in the spermatogonia and spermatocytes at 72 and 96 h after initiation of cadmium exposure, and the pyknotic index, TUNEL-positive rate, and cleaved caspase-3-positive rate in the spermatogonia and spermatocytes of the cadmium-trea...

Azoospermic factor c (AZFc) deletions are the underlying cause in 10% of azoo- or severe oligozoospermia. Through extensive molecular analysis the precise genetic content of the AZFc region and the origin of its deletion have been determined. However, little is known about the effect of AZFc deletions on the functionality of germ cells at various developmental steps. The presence of normal, fer...

How Kit expression is regulated in the germline remains unknown. SOHLH1 and SOHLH2, two bHLH transcription factors specifically expressed in germ cells, are involved in spermatogonia and oocyte differentiation. In the male, deletion of each factor causes loss of Kit-expressing spermatogonia in the prepuberal testis. In the female, SOHLH1 and SOHLH2 ablations cause oocyte loss in the neonatal ov...

Spermatogenesis is sensitive to the chemotherapeutic drug cyclophosphamide, which decreases the patients' sperm count. Since the recovery of fertility is dependent on regeneration from stem cells, in the present study we evaluated the ability of cyclophosphamide-exposed stem spermatogonia from mice to regenerate spermatogenesis in situ and after transplantation. When seven doses of cyclophospha...

Mice were injected intraperitoneally with 15 microc of H(3)-thymidine. The time course of the labeling in spermatogonia and spermatocytes was studied by using autoradiography on 5 micro sections stained by the periodic acid-Schiff method and hematoxylin over a period of 57 hours after injection. Four generations of type A (called AI, AII, AIII, and AIV), one of intermediate, and one of type B s...

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...