title: Macrophages Contribute to the Spermatogonial Niche in the Adult Testis.
abstract: The testis produces sperm throughout the male reproductive lifespan by balancing self-renewal and differentiation of spermatogonial stem cells (SSCs). Part of the SSC niche is thought to lie outside the seminiferous tubules of the testis; however, specific interstitial components of the niche that regulate spermatogonial divisions and differentiation remain undefined. We identified distinct populations of testicular macrophages, one of which lies on the surface of seminiferous tubules, in close apposition to areas of tubules enriched for undifferentiated spermatogonia. These macrophages express spermatogonial proliferation- and differentiation-inducing factors, such as colony-stimulating factor 1 (CSF1) and enzymes involved in retinoic acid (RA) biosynthesis. We show that transient depletion of macrophages leads to a disruption in spermatogonial differentiation. These findings reveal an unexpected role for macrophages in the spermatogonial niche in the testis and raise the possibility that macrophages play previously unappreciated roles in stem/progenitor cell regulation in other tissues.
authors.affiliation: Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA. Electronic address: tony.defalco@cchmc.org.
authors.forename: Tony
authors.initials: T
authors.lastname: DeFalco
authors.affiliation: Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Potter
authors.affiliation: Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
authors.forename: Alyna V
authors.initials: AV
authors.lastname: Williams
authors.affiliation: Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
authors.forename: Brittain
authors.initials: B
authors.lastname: Waller
authors.affiliation: Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Kan
authors.affiliation: Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Blanche
authors.initials: B
authors.lastname: Capel
mesh_terms: D000818:Animals; D003115:Colony-Stimulating Factors / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013091:Spermatogenesis; D013093:Spermatogonia / Q000166:cytology* / Q000378:metabolism; D055153:Stem Cell Niche; D013737:Testis / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D014212:Tretinoin / Q000378:metabolism
chemical_list: D003115:Colony-Stimulating Factors; D014212:Tretinoin