rakud, mis on pärit tüvirakkudest ja on kitsalt spetsialiseeritud arenema vaid kindlaks rakutüübiks ning annavad paljunemisel ainult seda tüüpi rakke, A progenitor cell can differentiate into a specific type of cell, but is already more specific than a stem cell and is pushed to differentiate into its "target" cell. 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 time.