stem cell PMID:27013241 PMID:20422023 PMID:22385657 PMID:24063805 PMID:26062938 PMID:23123964 PMID:29124009 PMID:27501047 CL:0000034 PMID:27034770 PMID:19805089 PMID:17376870 PMID:24173799 A relatively undifferentiated cell that retains the ability to divide and proliferate throughout life to provide progenitor cells that can differentiate into specialized cells. https://doi.org/10.1101/279364 PMID:26651295 https://orcid.org/0000-0003-2569-1939 | https://orcid.org/0000-0002-7535-4407 Planarian_Anatomy PMID:26711341 PMID:23318635 PMID:21937596 PMID:20707997 cell