“…Based on the prevalence of periodic oscillatory gene expression in cells and tissues of various organisms (Eser et al, 2014 (Imayoshi & Kageyama, 2014;Roese-Koerner, Stappert, & Brustle, 2017;Shimojo & Kageyama, 2016;Suzuki, Furusawa, & Kaneko, 2011;William et al, 2007), and tanycytes are now recognized as adult neural stem and progenitor cells because they can self-renew and also differentiate into neurons or astrocytes (Chaker et al, 2016;Haan et al, 2013;Lee et al, 2012;Robins et al, 2013;Xu et al, 2005). Thus, periodic gene expression in tanycytes may be a characteristic related specifically to their stem/progenitor cell properties, which is also supported by the fact that Prss56 is specific to stem or progenitor cells in the brain, retina and skin (…”