Vaccinia-related kinase 1 (VRK1) is a crucial protein kinase for mitotic regulation. VRK1 is known to play a role in germ cell development, and its deficiency results in sterility. Here we describe that VRK1 is essential for the maintenance of spermatogonial stem cells. To determine whether VRK1 plays a role in these cells, we assessed the population size of undifferentiated spermatogonia. Flow...

Spermatogonial stem cells (SSCs) are responsible for the preservation of spermatogenesis throughout a man's adult reproductive life. Like other stem cells in the body, SSCs can either self-renew or differentiate. Recent research has shown that SSCs can be considered as multipotent stem cells which can differentiate into cell types other than exclusively gametes. SSC proliferation is a well regu...

The use of a transgenic line of rats that express enhanced GFP (EGFP) exclusively in the germ line has allowed a separation of feeder layers and contaminating testis somatic cells from germ cells and the identification of a set of spermatogonial stem cell marker transcripts. With these molecular markers as a guide, we have now devised culture conditions where rat spermatogonial stem cells renew...