Lin28 Pax6 DAPI photoWe are interested in understanding how a seemingly homogeneous population of stem cells generates immense and unrivalled cellular diversity of the central nervous system (CNS). This is a fundamental question in neurobiology with direct implication for understanding how and why a particular neuronal type degenerates and formulating cell-based therapeutic approaches. We use retina as a CNS model to examine the cross talk between the cell-intrinsic (transcriptional regulators and microRNAs) and cell-extrinsic (niche-based signaling, for example the Notch pathway) factors that regulate the maintenance and differentiation of stem cells. This approach has been instrumental in identifying cellular and molecular targets for potential therapeutic regeneration in age-related blinding diseases such as age-related macular degeneration (AMD) and glaucoma. The figure shows retinal progenitor cells (RPCs) in a neurosphere (image: Xia Xiaohuan).