The most important difference between stem cells and progenitor cells is that stem cells can replicate indefinitely, whereas progenitor cells can divide only a limited number of times.

For instance, the first generation of stars have yet to be directly observed, but the progenitor of GRB 090423 may belong to this class.

In religion, for example, John Wycliffe, the intellectual progenitor of the Protestant Reformation, referred to Alhazen in discussing the seven deadly sins in terms of the distortions in the seven types of mirrors analyzed in De aspectibus .

Member of the Gallic group of irregular satellites, sharing a similar orbit and displaying a similar light red colour, Erriapus is thought to have its origin in a break up of a common progenitor of the group or to be a fragment of Albiorix.

You know, culture was born of the imagination, and the imagination the imagination as we know it came into being when our species descended from our progenitor, Homo erectus, and, infused with consciousness, began a journey that would carry it to every corner of the habitable world.