Mice were injected intraperitoneally with 15 #c of H3-thymidine. The time course of the labeling in spermatogonia and spermatocytes was studied by using autoradiography on 5 # sections stained by the periodic acid-Schiff method and hematoxylin over a period of 57 hours after injection. Four generations of t~pe A (called AI, AII, Am, and Air), oneofintermediate, and one of type B spermatogonia o...

The commonly applied classification systems of fish gonad maturity divide the maturation process into certain stages. However, the scales do not entirely reflect the continuity of the maturation process. Based on light microscope observations, the paper describes a comprehensive pattern of testicular transformations during maturation. The study was carried out on precocious underyearling and 1-...

Stem cells give rise to differentiated cell types but also preserve their undifferentiated state through cell self-renewal. With the use of transgenic mice, we found that the RNA-binding protein NANOS2 is essential for maintaining spermatogonial stem cells. Lineage-tracing analyses revealed that undifferentiated spermatogonia expressing Nanos2 self-renew and generate the entire spermatogenic ce...

Although the ability of engrafted stem cells to regenerate tissue has received much attention, the molecular mechanisms controlling regeneration are poorly understood. In the Drosophila male germline, local activation of the Janus kinase-signal transducer and activator of transcription (Jak-STAT) pathway maintains stem cells; germline stem cells lacking Jak-STAT signaling differentiate into spe...

Male rabbits, aged 4.5 months, were subjected to graded total gamma irradiations of 0.5 Gy, 1.5 Gy, 2.5 Gy and 3.0 Gy with a dose density of 24 Gy/min. The genetic effects in spermatogonia were assessed 3 months later using cytogenetic analysis of chromosomal preparations. The data showed a dose-dependent increase in the frequency of reciprocal translocations, induced in spermatogonia and detec...

A 400 bp fragment of the spermatogonia-specific Stra8 locus was sufficient to direct gene expression to the germinal stem cells in transgenic mice. A fractionation procedure was devised, based on immunomagnetic sorting of cells in which the promoter drives the expression of a surface functionally neutral protein tag. The purified cells expressed the known molecular markers of spermatogonia Rbm,...