The Male Stem Cell Niche: Insights from Drosophila and Mammalian Model Systems

Stem cells are indispensable for multicellular development since they provide the cells that built up our bodies and renew damaged cells during adult life. Specialized inputs for proper stem cell function lay in a local tissue microenvironment, the stem cell niche that homes them and regulates the balance between stem cell renewal and differentiation. Spermatogenesis is a classical adult stem cell system in which germline stem cells generate the male gametes that transmit genetic information to the progeny of the organism. A common theme in spermatogenesis across various species is that male stem cell niche and testis morphogenesis relies on intrinsic germline stem cell factors but also on the physical contact and diffusible signals exchanged between the germline and the juxtaposed somatic cell populations. This book chapter addresses the current state of the art of the male stem cell niche in Drosophila and mammalian testes. We review well-established and recent findings on male stem cell niche architecture, and on how the niche and germline cross-talk shapes spermatogenesis and promotes normal sperm production, which is of outmost importance for all sexually reproductive organisms. Finally, we compare Drosophila and mammalian male stem cell niches, discuss the differences and similarities, and provide stimulating insights on the basic organizing and regulatory strategies adapted in each model organism.