The maintenance of cycling cell lineages relies on undifferentiated subpopulations consisting of stem and progenitor pools. Features that delineate these cell types are undefined for many lineages, including spermato-genesis, which is supported by an undifferentiated spermatogonial population. Here, we generated a transgenic mouse line in which spermatogonial stem cells are marked by expression of an inhibitor of differentiation 4 (Id4)-green fluorescent protein (Gfp) transgene. We found that Id4-Gfp+ cells exist primarily as a subset of the type Asingle pool, and their frequency is greatest in neonatal development and then decreases in proportion during establishment of the spermatogenic lineage, eventually comprising ~ 2% of the undifferentiated spermatogonial population in adulthood. RNA sequencing analysis revealed that expression of 11 and 25 genes is unique for the Id4-Gfp+/stem cell and Id4-Gfp-/progenitor fractions, respectively. Collectively, these findings provide the first definitive evidence that stem cells exist as a rare subset of the Asingle pool and reveal transcriptome features distinguishing stem cell and progenitor states within the mammalian male germline.
All Science Journal Classification (ASJC) codes