Stem cells: to be and not to be.
D000818:Animals; D002454:Cell Differentiation; D002455:Cell Division; D016764:Cell Polarity; D004330:Drosophila / Q000166:cytology / Q000196:embryology; D008297:Male; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D013737:Testis / Q000166:cytology / Q000378:metabolism