title: Functional identification of the actual and potential stem cell compartments in mouse spermatogenesis.
abstract: To clarify the mechanisms that support the continuity of actively cycling tissues of long-lived organisms, we investigated the composition of a mouse spermatogenic stem cell system by pulse-chase of the undifferentiated spermatogonia, the population responsible for stem cell functions, in combination with transplantation and regeneration assays after pulse-labeling. We demonstrate that in addition to "actual stem cells," which are indeed self-renewing, a second population ("potential stem cells") also exists, which is capable of self-renewing but do not self-renew in the normal situation. Potential stem cells rapidly turn over in normal testes, suggesting that they belong to the transit-amplifying, rather than the dormant, population. During the long natural course, actual stem cells are occasionally lost and compensated for by progeny of their neighbors. In this process, potential stem cells are postulated to shift their modes from transit amplification to self-renewal, thus playing an essential role to ensure spermatogenesis integrity.
authors.affiliation: Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Yo-Ichi
authors.initials: Y
authors.lastname: Nabeshima
authors.forename: Shosei
authors.initials: S
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D002451:Cell Compartmentation; D002454:Cell Differentiation; D003114:Colony-Forming Units Assay; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D012038:Regeneration; D013091:Spermatogenesis / Q000502:physiology*; D013093:Spermatogonia / Q000166:cytology; D013234:Stem Cells / Q000166:cytology*; D013629:Tamoxifen / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000502:physiology / Q000637:transplantation; D013997:Time Factors
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009419:Nerve Tissue Proteins; D013629:Tamoxifen; C407737:Neurog3 protein, mouse