Abstract
Male germline or spermatogonial stem cells (SSCs) are conserved across many species and essential for uninterrupted production of sperm over long periods of reproductive life span. A better understanding of SSC biology provides limitless opportunities in male reproductive health, fertility preservation, and regenerative medicine. Although several potential markers define SSCs, not many definitive markers exist that are specific for a rare subset of SSCs that self-renew and have the ability to give rise to other progenitors, eventually contributing to all stages of spermatogenesis. In the September 2014 issue of the JCI, Aloisio and colleagues report that PAX7 is a new marker expressed uniquely in a rare subset of SSCs in mouse testes. PAX7+ cells fulfill all the criteria required for bona fide SSCs. Surprisingly, male germline-specific deletion of Pax7 indicates that it is dispensable for spermatogenesis.