Testicular Architecture Is Critical for Mediation of Retinoic Acid Responsiveness by Undifferentiated Spermatogonial Subtypes in the Mouse

Publication date: Available online 1 February 2018 Source:Stem Cell Reports Author(s): Tessa Lord, Melissa J. Oatley, Jon M. Oatley Spermatogenesis requires retinoic acid (RA) induction of the undifferentiated to differentiating transition in transit amplifying (TA) progenitor spermatogonia, whereas continuity of the spermatogenic lineage relies on the RA response being suppressed in spermatogonial stem cells (SSCs). Here, we discovered that, in mouse testes, both spermatogonial populations possess intrinsic RA-response machinery and exhibit hallmarks of the differentiating transition following direct exposure to RA, including loss of SSC regenerative capacity. We determined that SSCs are only resistant to RA-driven differentiation when situated in the normal topological organization of the testis. Furthermore, we show that the soma is instrumental in “priming” TA progenitors for RA-induced differentiation through elevated RA receptor expression. Collectively, these findings indicate that SSCs and TA progenitor spermatogonia inhabit disparate niche microenvironments within seminiferous tubules that are critical for mediating extrinsic cues that drive fate decisions. Teaser Lord et al. have demonstrated that, contrary to previous assumptions, spermatogonial stem cells do express a functional complement of retinoic acid and retinoid X receptors (RARs/RXRs) and rely on protection from an undisturbed niche microenvironment to prevent loss of the spermatogenic reservoir ...
Source: Stem Cell Reports - Category: Stem Cells Source Type: research