Practice question

The fundamental distinction lies in lifespan and self-renewal capacity. Stem cells maintain indefinite self-renewal through telomerase activity, DNA repair proficiency, and symmetric self-renewing divisions, persisting throughout organismal lifetime. Progenitor or transit-amplifying cells exhibit limited proliferative potential, typically fewer than ten divisions, before senescence or terminal differentiation. Stem cells also retain broader potency and ability to regenerate tissue after injury, while progenitors are more fate-restricted. Both can differentiate, but only stem cells combine lifelong persistence with self-renewal, making them true reservoir for tissue turnover.