title: Ontogenesis as a two-level process.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002454:Cell Differentiation; D003491:Cybernetics; D005314:Embryonic and Fetal Development; D006801:Humans; D008954:Models, Biological; D008967:Molecular Biology; D009024:Morphogenesis; D009369:Neoplasms / Q000503:physiopathology; D013724:Teratoma / Q000503:physiopathology