title: Directive versus permissive induction: a working hypothesis.
mesh_terms: D000818:Animals; D002356:Cartilage / Q000196:embryology; D002454:Cell Differentiation; D002490:Central Nervous System / Q000196:embryology; D003743:Dental Enamel / Q000196:embryology; D004627:Embryonic Induction; D004848:Epithelium; D007684:Kidney Tubules / Q000196:embryology; D009024:Morphogenesis; D012867:Skin / Q000196:embryology; D014070:Tooth / Q000196:embryology