RT Journal Article SR Electronic T1 Expression of Wnt5a defines the major progenitors of fetal and adult Leydig cells JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.07.25.221069 DO 10.1101/2020.07.25.221069 A1 Herta Ademi A1 Isabelle Stévant A1 Chris M Rands A1 Béatrice Conne A1 Serge Nef YR 2020 UL http://biorxiv.org/content/early/2020/07/26/2020.07.25.221069.abstract AB Leydig cells (LCs) are the major androgen-producing cells in the testes. They arise from steroidogenic progenitors, whose origins, maintenance and differentiation dynamics remain largely unknown. Here, we identified Wnt5a as a specific marker of steroidogenic progenitors, whose expression begins at around E11.5-E12.5 in interstitial cells of the fetal mouse testis. In vivo lineage tracing indicates that Wnt5a-expressing progenitors are initially present in large numbers in the fetal testis and then progressively decrease as development progresses. We provide evidence that Wnt5a-expressing cells are bona fide progenitors of peritubular myoid cells as well as fetal and adult LCs, contributing to most of the LCs present in the fetal and adult testis. Additionally, we show in the adult testis that Wnt5a expression is restricted to a subset of LCs exhibiting a slow but noticeable clonal expansion, revealing hitherto unappreciated proliferation of fully differentiated LCs as a contribution to the adult LC pool.Competing Interest StatementThe authors have declared no competing interest.